diff --git a/src/components/base/NumberInputBase.ts b/src/components/base/NumberInputBase.ts
index b8a3180f..e6b2a2fe 100644
--- a/src/components/base/NumberInputBase.ts
+++ b/src/components/base/NumberInputBase.ts
@@ -40,11 +40,13 @@ export function useNumberInputBase(props: NumberInputProps, emit: NumberInputEmi
 
         let finalValue = '';
         for (let i = 0; i < value.length; i++) {
-            if (!NumeralSystem.WesternArabicNumerals.isDigit(value[i]) && !numeralSystem.value.isDigit(value[i]) && value[i] !== '-' && value[i] !== decimalSeparator) {
+            const ch = value.charAt(i);
+
+            if (!NumeralSystem.WesternArabicNumerals.isDigit(ch) && !numeralSystem.value.isDigit(ch) && ch !== '-' && ch !== decimalSeparator) {
                 break;
             }
 
-            finalValue += value[i];
+            finalValue += ch;
         }
 
         finalValue = numeralSystem.value.replaceLocalizedDigitsToWesternArabicDigits(finalValue);
@@ -104,14 +106,16 @@ export function useNumberInputBase(props: NumberInputProps, emit: NumberInputEmi
             const decimalSeparator = getCurrentDecimalSeparator();
 
             if (newValue[0] === '-' || newValue[0] === decimalSeparator) {
-                actualNumeralSystem = NumeralSystem.detect(newValue[1]);
+                actualNumeralSystem = NumeralSystem.detect(newValue.charAt(1));
             } else {
-                actualNumeralSystem = NumeralSystem.detect(newValue[0]);
+                actualNumeralSystem = NumeralSystem.detect(newValue.charAt(0));
             }
 
             if (actualNumeralSystem && (actualNumeralSystem.type === NumeralSystem.WesternArabicNumerals.type || actualNumeralSystem.type === numeralSystem.value.type)) {
                 for (let i = 0; i < newValue.length; i++) {
-                    if (!NumeralSystem.WesternArabicNumerals.isDigit(newValue[i]) && !numeralSystem.value.isDigit(newValue[i]) && newValue[i] !== '-' && newValue[i] !== decimalSeparator) {
+                    const ch = newValue.charAt(i);
+
+                    if (!NumeralSystem.WesternArabicNumerals.isDigit(ch) && !numeralSystem.value.isDigit(ch) && ch !== '-' && ch !== decimalSeparator) {
                         break;
                     }
 
diff --git a/src/components/base/PieChartBase.ts b/src/components/base/PieChartBase.ts
index 23b9abf8..92267b16 100644
--- a/src/components/base/PieChartBase.ts
+++ b/src/components/base/PieChartBase.ts
@@ -44,8 +44,7 @@ export function usePieChartBase(props: CommonPieChartProps) {
     const validItems = computed<CommonPieChartDataItem[]>(() => {
         let totalValidValue = 0;
 
-        for (let i = 0; i < props.items.length; i++) {
-            const item = props.items[i];
+        for (const item of props.items) {
             const value = item[props.valueField];
 
             if (isNumber(value) && value > 0 && (!props.hiddenField || !item[props.hiddenField])) {
@@ -55,8 +54,7 @@ export function usePieChartBase(props: CommonPieChartProps) {
 
         const validItems: CommonPieChartDataItem[] = [];
 
-        for (let i = 0; i < props.items.length; i++) {
-            const item = props.items[i];
+        for (const item of props.items) {
             const value = item[props.valueField];
             const percent = props.percentField ? item[props.percentField] : -1;
 
diff --git a/src/components/base/ScheduleFrequencySelectionBase.ts b/src/components/base/ScheduleFrequencySelectionBase.ts
index 1227c22b..6da12931 100644
--- a/src/components/base/ScheduleFrequencySelectionBase.ts
+++ b/src/components/base/ScheduleFrequencySelectionBase.ts
@@ -44,9 +44,9 @@ export function useScheduleFrequencySelectionBase() {
         const values = value.split(',');
         const ret: number[] = [];
 
-        for (let i = 0; i < values.length; i++) {
-            if (values[i]) {
-                ret.push(parseInt(values[i]));
+        for (const value of values) {
+            if (value) {
+                ret.push(parseInt(value));
             }
         }
 
diff --git a/src/components/common/PinCodeInput.vue b/src/components/common/PinCodeInput.vue
index ecceab3b..7b65f49d 100644
--- a/src/components/common/PinCodeInput.vue
+++ b/src/components/common/PinCodeInput.vue
@@ -1,15 +1,15 @@
 <template>
     <div class="pin-codes-input" :style="`grid-template-columns: repeat(${length}, minmax(0, 1fr))`">
         <div class="pin-code-input pin-code-input-outline"
-             :class="{ 'pin-code-input-focued': codes[index].focused }" :key="index"
+             :class="{ 'pin-code-input-focued': codes[index]!.focused }" :key="index"
              v-for="(_, index) in codes">
             <input ref="pin-code-input" min="0" maxlength="1" pattern="[0-9]*"
-                   :value="codes[index].value"
-                   :type="codes[index].inputType"
+                   :value="codes[index]!.value"
+                   :type="codes[index]!.inputType"
                    :disabled="disabled ? true : undefined"
                    :autofocus="autofocus && index === 0 ? true : undefined"
-                   @focus="codes[index].focused = true"
-                   @blur="codes[index].focused = false"
+                   @focus="codes[index]!.focused = true"
+                   @blur="codes[index]!.focused = false"
                    @keydown="onKeydown(index, $event)"
                    @paste="onPaste(index, $event)"
                    @change="onInput(index, $event)"
@@ -57,9 +57,9 @@ const numeralSystem = computed<NumeralSystem>(() => getCurrentNumeralSystemType(
 const finalPinCode = computed<string>(() => {
     let ret = '';
 
-    for (let i = 0; i < codes.value.length; i++) {
-        if (codes.value[i].value) {
-            ret += codes.value[i].value;
+    for (const code of codes.value) {
+        if (code.value) {
+            ret += code.value;
         } else {
             break;
         }
@@ -80,7 +80,7 @@ function init(length: number, value: string): void {
         };
 
         if (value && value[i]) {
-            code.value = value[i];
+            code.value = value.charAt(i);
 
             if (props.secure) {
                 code.inputType = 'password';
@@ -95,12 +95,14 @@ function autoFillText(index: number, text: string): void {
     let lastIndex = index;
 
     for (let i = index, j = 0; i < codes.value.length && j < text.length; i++, j++) {
-        if (text[j] < '0' || text[j] > '9') {
-            codes.value[i].value = '';
+        const ch = text.charAt(j);
+
+        if (ch < '0' || ch > '9') {
+            codes.value[i]!.value = '';
             break;
         }
 
-        codes.value[i].value = text[j];
+        codes.value[i]!.value = ch;
         setInputType(i);
         lastIndex = i;
     }
@@ -117,23 +119,29 @@ function setInputType(index: number): void {
         return;
     }
 
-    if (!codes.value[index].value) {
-        codes.value[index].inputType = 'tel';
+    const code = codes.value[index];
+
+    if (!code) {
         return;
     }
 
-    if (codes.value[index].inputTimer) {
+    if (!code.value) {
+        code.inputType = 'tel';
         return;
     }
 
-    codes.value[index].inputTimer = setTimeout(() => {
-        if (codes.value[index].value) {
-            codes.value[index].inputType = 'password';
+    if (code.inputTimer) {
+        return;
+    }
+
+    code.inputTimer = setTimeout(() => {
+        if (code.value) {
+            code.inputType = 'password';
         } else {
-            codes.value[index].inputType = 'tel';
+            code.inputType = 'tel';
         }
 
-        codes.value[index].inputTimer = null;
+        code.inputTimer = null;
     }, 300);
 }
 
@@ -205,7 +213,7 @@ function onKeydown(index: number, event: KeyboardEvent): void {
 
     if (event.key === 'Backspace' || event.key === 'Delete' || event.key === 'Del') {
         for (let i = index; i < codes.value.length; i++) {
-            codes.value[i].value = '';
+            codes.value[i]!.value = '';
             setInputType(i);
         }
 
@@ -227,7 +235,7 @@ function onKeydown(index: number, event: KeyboardEvent): void {
         }
 
         if (digit) {
-            codes.value[index].value = digit;
+            codes.value[index]!.value = digit;
             setInputType(index);
             setNextFocus(index);
 
diff --git a/src/components/common/TransactionCalendar.vue b/src/components/common/TransactionCalendar.vue
index 9fe3715c..ddea5e23 100644
--- a/src/components/common/TransactionCalendar.vue
+++ b/src/components/common/TransactionCalendar.vue
@@ -91,7 +91,7 @@ const alternateDates = computed<Record<TextualYearMonthDay, string> | undefined>
         return undefined;
     }
 
-    const allDates: CalendarAlternateDate[] | undefined = getCalendarAlternateDates({ year: parseInt(yearMonthDay[0]), month1base: parseInt(yearMonthDay[1]) })
+    const allDates: CalendarAlternateDate[] | undefined = getCalendarAlternateDates({ year: parseInt(yearMonthDay[0] as string), month1base: parseInt(yearMonthDay[1] as string) })
 
     if (!allDates) {
         return undefined;
diff --git a/src/components/desktop/AmountInput.vue b/src/components/desktop/AmountInput.vue
index daee27b1..395c897f 100644
--- a/src/components/desktop/AmountInput.vue
+++ b/src/components/desktop/AmountInput.vue
@@ -338,18 +338,20 @@ watch(currentValue, (newValue) => {
         const decimalSeparator = getCurrentDecimalSeparator();
 
         if (newValue[0] === '-' || newValue[0] === decimalSeparator) {
-            actualNumeralSystem = NumeralSystem.detect(newValue[1]);
+            actualNumeralSystem = NumeralSystem.detect(newValue.charAt(1));
         } else {
-            actualNumeralSystem = NumeralSystem.detect(newValue[0]);
+            actualNumeralSystem = NumeralSystem.detect(newValue.charAt(0));
         }
 
         if (actualNumeralSystem && (actualNumeralSystem.type === NumeralSystem.WesternArabicNumerals.type || actualNumeralSystem.type === numeralSystem.value.type)) {
             for (let i = 0; i < newValue.length; i++) {
-                if (!NumeralSystem.WesternArabicNumerals.isDigit(newValue[i]) && !numeralSystem.value.isDigit(newValue[i]) && newValue[i] !== '-' && newValue[i] !== decimalSeparator) {
+                const ch = newValue.charAt(i);
+
+                if (!NumeralSystem.WesternArabicNumerals.isDigit(ch) && !numeralSystem.value.isDigit(ch) && ch !== '-' && ch !== decimalSeparator) {
                     break;
                 }
 
-                finalValue += newValue[i];
+                finalValue += ch;
             }
 
             finalValue = numeralSystem.value.replaceWesternArabicDigitsToLocalizedDigits(finalValue);
diff --git a/src/components/desktop/PaginationButtons.vue b/src/components/desktop/PaginationButtons.vue
index 27f484db..cc67538d 100644
--- a/src/components/desktop/PaginationButtons.vue
+++ b/src/components/desktop/PaginationButtons.vue
@@ -52,7 +52,7 @@ import { ref, computed } from 'vue';
 
 import { useI18n } from '@/locales/helpers.ts';
 
-import type { NameNumeralValue } from '@/core/base.ts';
+import { type NameNumeralValue, keys } from '@/core/base.ts';
 import type { NumeralSystem } from '@/core/numeral.ts';
 import type { ComponentDensity } from '@/lib/ui/desktop.ts';
 
@@ -94,11 +94,7 @@ const currentPage = computed<number>({
         if (value && value >= 1 && value <= props.totalPageCount) {
             emit('update:modelValue', value);
 
-            for (const key in showMenus.value) {
-                if (!Object.prototype.hasOwnProperty.call(showMenus.value, key)) {
-                    continue;
-                }
-
+            for (const key of keys(showMenus.value)) {
                 showMenus.value[key] = false;
             }
         }
diff --git a/src/components/desktop/PieChart.vue b/src/components/desktop/PieChart.vue
index f6bfd4b0..4f3efe80 100644
--- a/src/components/desktop/PieChart.vue
+++ b/src/components/desktop/PieChart.vue
@@ -13,6 +13,7 @@ import type { CallbackDataParams } from 'echarts/types/dist/shared';
 import { useI18n } from '@/locales/helpers.ts';
 import { type CommonPieChartDataItem, type CommonPieChartProps, usePieChartBase } from '@/components/base/PieChartBase.ts'
 
+import { itemAndIndex } from '@/core/base.ts';
 import type { ColorStyleValue } from '@/core/color.ts';
 import { ThemeType } from '@/core/theme.ts';
 
@@ -41,8 +42,7 @@ const isDarkMode = computed<boolean>(() => theme.global.name.value === ThemeType
 const itemsMap = computed<Record<string, Record<string, unknown>>>(() => {
     const map: Record<string, Record<string, unknown>> = {};
 
-    for (let i = 0; i < props.items.length; i++) {
-        const item = props.items[i];
+    for (const item of props.items) {
         let id = '';
 
         if (props.idField && item[props.idField]) {
@@ -60,8 +60,7 @@ const itemsMap = computed<Record<string, Record<string, unknown>>>(() => {
 const seriesData = computed<DesktopPieChartDataItem[]>(() => {
     const ret: DesktopPieChartDataItem[] = [];
 
-    for (let i = 0; i < validItems.value.length; i++) {
-        const item = validItems.value[i];
+    for (const item of validItems.value) {
         ret.push({
             ...item,
             itemStyle: {
@@ -75,9 +74,7 @@ const seriesData = computed<DesktopPieChartDataItem[]>(() => {
 });
 
 const hasUnselectedItem = computed<boolean>(() => {
-    for (let i = 0; i < validItems.value.length; i++) {
-        const item = validItems.value[i];
-
+    for (const item of validItems.value) {
         if (selectedLegends.value && !selectedLegends.value[item.id]) {
             return true;
         }
@@ -91,9 +88,7 @@ const firstItemAndHalfCurrentItemTotalPercent = computed<number>(() => {
     let firstValue = null;
     let firstToCurrentTotalValue = 0;
 
-    for (let i = 0; i < validItems.value.length; i++) {
-        const item = validItems.value[i];
-
+    for (const [item, index] of itemAndIndex(validItems.value)) {
         if (selectedLegends.value && !selectedLegends.value[item.id]) {
             continue;
         }
@@ -103,9 +98,9 @@ const firstItemAndHalfCurrentItemTotalPercent = computed<number>(() => {
         }
 
         if (firstValue !== null) {
-            if (i < selectedIndex.value) {
+            if (index < selectedIndex.value) {
                 firstToCurrentTotalValue += item.value;
-            } else if (i === selectedIndex.value) {
+            } else if (index === selectedIndex.value) {
                 firstToCurrentTotalValue += item.value / 2;
             }
         }
@@ -241,11 +236,9 @@ function onLegendSelectChanged(e: { selected: Record<string, boolean> }): void {
     if (!selectedItem || !selectedLegends.value[selectedItem.id]) {
         let newSelectedIndex = 0;
 
-        for (let i = 0; i < validItems.value.length; i++) {
-            const item = validItems.value[i];
-
+        for (const [item, index] of itemAndIndex(validItems.value)) {
             if (selectedLegends.value[item.id]) {
-                newSelectedIndex = i;
+                newSelectedIndex = index;
                 break;
             }
         }
diff --git a/src/components/desktop/ScheduleFrequencySelect.vue b/src/components/desktop/ScheduleFrequencySelect.vue
index 367c0526..65df22d1 100644
--- a/src/components/desktop/ScheduleFrequencySelect.vue
+++ b/src/components/desktop/ScheduleFrequencySelect.vue
@@ -138,9 +138,9 @@ function updateFrequencyValue(value: number, selected: boolean | null): void {
     const currentFrequencyValues = frequencyValue.value;
     const newFrequencyValues: number[] = [];
 
-    for (let i = 0; i < currentFrequencyValues.length; i++) {
-        if (currentFrequencyValues[i] !== value || selected) {
-            newFrequencyValues.push(currentFrequencyValues[i]);
+    for (const currentFrequencyValue of currentFrequencyValues) {
+        if (currentFrequencyValue !== value || selected) {
+            newFrequencyValues.push(currentFrequencyValue);
         }
     }
 
diff --git a/src/components/desktop/StepsBar.vue b/src/components/desktop/StepsBar.vue
index 4f485d90..f75e0897 100644
--- a/src/components/desktop/StepsBar.vue
+++ b/src/components/desktop/StepsBar.vue
@@ -48,6 +48,7 @@ import { computed } from 'vue';
 
 import { useI18n } from '@/locales/helpers.ts';
 
+import { itemAndIndex } from '@/core/base.ts';
 import { NumeralSystem } from '@/core/numeral.ts';
 
 export interface StepBarItem {
@@ -87,9 +88,9 @@ function isStepActive(step: StepBarItem): boolean {
 }
 
 function isStepCompleted(stepIndex: number): boolean {
-    for (let i = 0; i < props.steps.length; i++) {
-        if (props.steps[i].name === props.currentStep) {
-            return stepIndex < i;
+    for (const [step, index] of itemAndIndex(props.steps)) {
+        if (step.name === props.currentStep) {
+            return stepIndex < index;
         }
     }
 
diff --git a/src/components/mobile/NumberPadSheet.vue b/src/components/mobile/NumberPadSheet.vue
index 02eeeb9a..4dc8d58f 100644
--- a/src/components/mobile/NumberPadSheet.vue
+++ b/src/components/mobile/NumberPadSheet.vue
@@ -50,7 +50,7 @@
                     <span class="numpad-button-text numpad-button-text-normal">{{ decimalSeparator }}</span>
                 </f7-button>
                 <f7-button class="numpad-button numpad-button-num" v-if="!supportDecimalSeparator" @click="inputDoubleNum(0)">
-                    <span class="numpad-button-text numpad-button-text-normal">{{ digits[0] + digits[0] }}</span>
+                    <span class="numpad-button-text numpad-button-text-normal">{{ `${digits[0]}${digits[0]}` }}</span>
                 </f7-button>
                 <f7-button class="numpad-button numpad-button-num" @click="inputNum(0)">
                     <span class="numpad-button-text numpad-button-text-normal">{{ digits[0] }}</span>
@@ -114,11 +114,11 @@ const digits = computed<string[]>(() => getAllLocalizedDigits());
 const decimalSeparator = computed<string>(() => getCurrentDecimalSeparator());
 
 const supportDecimalSeparator = computed<boolean>(() => {
-    if (!props.currency || !ALL_CURRENCIES[props.currency] || !isNumber(ALL_CURRENCIES[props.currency].fraction)) {
+    if (!props.currency || !ALL_CURRENCIES[props.currency] || !isNumber(ALL_CURRENCIES[props.currency]!.fraction)) {
         return true;
     }
 
-    return (ALL_CURRENCIES[props.currency].fraction as number) > 0;
+    return (ALL_CURRENCIES[props.currency]!.fraction as number) > 0;
 });
 
 const currentDisplay = computed<string>(() => {
diff --git a/src/components/mobile/PieChart.vue b/src/components/mobile/PieChart.vue
index 19817c45..d55d3ce5 100644
--- a/src/components/mobile/PieChart.vue
+++ b/src/components/mobile/PieChart.vue
@@ -105,8 +105,8 @@ const circumference: number = diameter * Math.PI;
 const totalValidValue = computed<number>(() => {
     let totalValidValue = 0;
 
-    for (let i = 0; i < validItems.value.length; i++) {
-        totalValidValue += validItems.value[i].value;
+    for (const item of validItems.value) {
+        totalValidValue += item.value;
     }
 
     return totalValidValue;
@@ -120,7 +120,7 @@ const itemCommonDashOffset = computed<number>(() => {
     let offset = 0;
 
     for (let i = 0; i < Math.min(selectedIndex.value + 1, validItems.value.length); i++) {
-        const item = validItems.value[i];
+        const item = validItems.value[i] as CommonPieChartDataItem;
 
         if (item.actualPercent > 0) {
             if (i === selectedIndex.value) {
@@ -154,9 +154,7 @@ function getItemStrokeDash(item: CommonPieChartDataItem): string {
 function getItemDashOffset(item: CommonPieChartDataItem, items: CommonPieChartDataItem[], offset?: number): number {
     let allPreviousPercent = 0;
 
-    for (let i = 0; i < items.length; i++) {
-        const curItem = items[i];
-
+    for (const curItem of items) {
         if (curItem === item) {
             break;
         }
@@ -189,7 +187,7 @@ const selectedItem = computed<CommonPieChartDataItem | null>(() => {
         index = 0;
     }
 
-    return validItems.value[index];
+    return validItems.value[index] ?? null;
 });
 
 function switchSelectedIndex(index: number): void {
diff --git a/src/consts/currency.ts b/src/consts/currency.ts
index f2c82c93..b2d05768 100644
--- a/src/consts/currency.ts
+++ b/src/consts/currency.ts
@@ -1284,5 +1284,5 @@ export const ALL_CURRENCIES: Record<string, CurrencyInfo> = {
 };
 
 export const DEFAULT_CURRENCY_SYMBOL: string = '¤';
-export const DEFAULT_CURRENCY_CODE: string = ALL_CURRENCIES['USD'].code;
+export const DEFAULT_CURRENCY_CODE: string = (ALL_CURRENCIES['USD'] as CurrencyInfo).code;
 export const PARENT_ACCOUNT_CURRENCY_PLACEHOLDER: string = '---';
diff --git a/src/consts/icon.ts b/src/consts/icon.ts
index 770ceba1..443a035a 100644
--- a/src/consts/icon.ts
+++ b/src/consts/icon.ts
@@ -161,7 +161,7 @@ export const ALL_ACCOUNT_ICONS: Record<string, IconInfo> = {
     }
 };
 
-export const DEFAULT_ACCOUNT_ICON = ALL_ACCOUNT_ICONS[DEFAULT_ACCOUNT_ICON_ID];
+export const DEFAULT_ACCOUNT_ICON: IconInfo = ALL_ACCOUNT_ICONS[DEFAULT_ACCOUNT_ICON_ID] as IconInfo;
 
 export const DEFAULT_CATEGORY_ICON_ID = '1';
 export const AUTOMATICALLY_CREATED_CATEGORY_ICON_ID = '561';
@@ -837,4 +837,4 @@ export const ALL_CATEGORY_ICONS: Record<string, IconInfo> = {
     }
 };
 
-export const DEFAULT_CATEGORY_ICON = ALL_CATEGORY_ICONS[DEFAULT_CATEGORY_ICON_ID];
+export const DEFAULT_CATEGORY_ICON: IconInfo = ALL_CATEGORY_ICONS[DEFAULT_CATEGORY_ICON_ID] as IconInfo;
diff --git a/src/core/base.ts b/src/core/base.ts
index a19edcb0..6d61fe38 100644
--- a/src/core/base.ts
+++ b/src/core/base.ts
@@ -3,6 +3,68 @@ export type PartialRecord<K extends keyof any, T> = {
     [P in K]?: T;
 }
 
+export function* itemAndIndex<T>(arr: T[]): Iterable<[T, number]> {
+    for (let i = 0; i < arr.length; i++) {
+        yield [arr[i], i] as [T, number];
+    }
+}
+
+export function* reversed<T>(arr: T[]): Iterable<T> {
+    for (let i = arr.length - 1; i >= 0; i--) {
+        yield arr[i] as T;
+    }
+}
+
+export function* reversedItemAndIndex<T>(arr: T[]): Iterable<[T, number]> {
+    for (let i = arr.length - 1; i >= 0; i--) {
+        yield [arr[i], i] as [T, number];
+    }
+}
+
+export function* entries<K extends string | number | symbol, V>(obj: Record<K, V>): Iterable<[K, V]> {
+    for (const key in obj) {
+        if (!Object.prototype.hasOwnProperty.call(obj, key)) {
+            continue;
+        }
+
+        yield [key, obj[key]] as [K, V];
+    }
+}
+
+export function* keys<K extends string | number | symbol, V>(obj: Record<K, V>): Iterable<K> {
+    for (const key in obj) {
+        if (!Object.prototype.hasOwnProperty.call(obj, key)) {
+            continue;
+        }
+
+        yield key as K;
+    }
+}
+
+export function* keysIfValueEquals<K extends string | number | symbol, V>(obj: Record<K, V>, value: V): Iterable<K> {
+    for (const key in obj) {
+        if (!Object.prototype.hasOwnProperty.call(obj, key)) {
+            continue;
+        }
+
+        if (obj[key] !== value) {
+            continue;
+        }
+
+        yield key as K;
+    }
+}
+
+export function* values<K extends string | number | symbol, V>(obj: Record<K, V>): Iterable<V> {
+    for (const key in obj) {
+        if (!Object.prototype.hasOwnProperty.call(obj, key)) {
+            continue;
+        }
+
+        yield obj[key] as V;
+    }
+}
+
 export interface NameValue {
     readonly name: string;
     readonly value: string;
diff --git a/src/core/fiscalyear.ts b/src/core/fiscalyear.ts
index 3bab25c9..5089abea 100644
--- a/src/core/fiscalyear.ts
+++ b/src/core/fiscalyear.ts
@@ -69,8 +69,8 @@ export class FiscalYearStart {
             return undefined;
         }
 
-        const month = parseInt(parts[0], 10);
-        const day = parseInt(parts[1], 10);
+        const month = parseInt(parts[0] as string, 10);
+        const day = parseInt(parts[1] as string, 10);
 
         return FiscalYearStart.of(month, day);
     }
@@ -87,7 +87,7 @@ export class FiscalYearStart {
     }
 
     private static isValidFiscalYearMonthDay(month: number, day: number): boolean {
-        return 1 <= month && month <= 12 && 1 <= day && day <= FiscalYearStart.MONTH_MAX_DAYS[month - 1];
+        return 1 <= month && month <= 12 && 1 <= day && day <= (FiscalYearStart.MONTH_MAX_DAYS[month - 1] as number);
     }
 }
 
diff --git a/src/core/numeral.ts b/src/core/numeral.ts
index fe91e87a..49114cc0 100644
--- a/src/core/numeral.ts
+++ b/src/core/numeral.ts
@@ -96,7 +96,7 @@ export class NumeralSystem implements TypeAndName {
             return '';
         }
 
-        return this.allDigits[digit];
+        return this.allDigits[digit] as string;
     }
 
     public parseInt(value: string): number {
@@ -136,11 +136,11 @@ export class NumeralSystem implements TypeAndName {
         let result = '';
 
         for (let i = 0; i < value.length; i++) {
-            const ch = value[i];
+            const ch = value.charAt(i);
 
             if (NumeralSystem.WesternArabicNumerals.isDigit(ch)) {
-                const digit = NumeralSystem.WesternArabicNumerals.digitsToWesternArabic[ch];
-                result += this.allDigits[digit];
+                const digit = NumeralSystem.WesternArabicNumerals.digitsToWesternArabic[ch] as number;
+                result += this.allDigits[digit] as string;
             } else {
                 result += ch;
             }
@@ -157,11 +157,11 @@ export class NumeralSystem implements TypeAndName {
         let result = '';
 
         for (let i = 0; i < value.length; i++) {
-            const ch = value[i];
+            const ch = value.charAt(i);
 
             if (this.isDigit(ch)) {
-                const digit = this.digitsToWesternArabic[ch];
-                result += NumeralSystem.WesternArabicNumerals.allDigits[digit];
+                const digit = this.digitsToWesternArabic[ch] as number;
+                result += NumeralSystem.WesternArabicNumerals.allDigits[digit] as string;
             } else {
                 result += ch;
             }
diff --git a/src/lib/__tests__/fiscal_year.ts b/src/lib/__tests__/fiscal_year.ts
index 7e357494..c55cfe01 100644
--- a/src/lib/__tests__/fiscal_year.ts
+++ b/src/lib/__tests__/fiscal_year.ts
@@ -168,7 +168,7 @@ describe('getFiscalYearStartUnixTime', () => {
                 const expected = testCase.expected[testFiscalYearStart.id];
                 const unixTimeISO = formatUnixTimeISO(startUnixTime);
 
-                expect({ unixTime: startUnixTime, ISO: unixTimeISO }).toStrictEqual({ unixTime: expected.unixTime, ISO: expected.unixTimeISO });
+                expect({ unixTime: startUnixTime, ISO: unixTimeISO }).toStrictEqual({ unixTime: expected!.unixTime, ISO: expected!.unixTimeISO });
             });
         });
     });
@@ -198,7 +198,7 @@ describe('getFiscalYearEndUnixTime', () => {
                 const expected = testCase.expected[testFiscalYearStart.id];
                 const unixTimeISO = formatUnixTimeISO(endUnixTime);
 
-                expect({ unixTime: endUnixTime, ISO: unixTimeISO }).toStrictEqual({ unixTime: expected.unixTime, ISO: expected.unixTimeISO });
+                expect({ unixTime: endUnixTime, ISO: unixTimeISO }).toStrictEqual({ unixTime: expected!.unixTime, ISO: expected!.unixTimeISO });
 
             });
         });
diff --git a/src/lib/calendar/__tests__/chinese_calendar.ts b/src/lib/calendar/__tests__/chinese_calendar.ts
index 2ce4f826..a377ba57 100644
--- a/src/lib/calendar/__tests__/chinese_calendar.ts
+++ b/src/lib/calendar/__tests__/chinese_calendar.ts
@@ -60,12 +60,12 @@ describe('getChineseYearMonthAllDayInfos', () => {
         }
 
         const items = line.split('\t');
-        const gregorianDate = items[0];
+        const gregorianDate = items[0] as string;
         const gregorianDateItems = gregorianDate.split('/');
-        const gregorianYear = parseInt(gregorianDateItems[0], 10);
-        const gregorianMonth = parseInt(gregorianDateItems[1], 10);
-        const chineseDay = items[1];
-        const solarTermName = items.length > 3 ? items[3] : '';
+        const gregorianYear = parseInt(gregorianDateItems[0] as string, 10);
+        const gregorianMonth = parseInt(gregorianDateItems[1] as string, 10);
+        const chineseDay = items[1] as string;
+        const solarTermName = items.length > 3 ? items[3] as string : '';
 
         if (currentYear > 0 && currentMonth > 0 && (gregorianYear !== currentYear || gregorianMonth !== currentMonth)) {
             allMonthChineseDays[`${currentYear}-${currentMonth}`] = currentMonthChineseDays;
@@ -93,10 +93,10 @@ describe('getChineseYearMonthAllDayInfos', () => {
     for (const yearMonth in allMonthChineseDays) {
         test(`returns correct chinese all dates in month for ${yearMonth}`, () => {
             const [yearStr, monthStr] = yearMonth.split('-');
-            const year = parseInt(yearStr);
-            const month = parseInt(monthStr);
-            const expectedChineseMonthOrDays = allMonthChineseDays[yearMonth];
-            const expectedSolarTermNames = allMonthSolarTermNames[yearMonth];
+            const year = parseInt(yearStr as string);
+            const month = parseInt(monthStr as string);
+            const expectedChineseMonthOrDays = allMonthChineseDays[yearMonth] as string[];
+            const expectedSolarTermNames = allMonthSolarTermNames[yearMonth] as string[];
 
             const actualChineseDates: ChineseYearMonthDayInfo[] | undefined = getChineseYearMonthAllDayInfos({
                 year: year,
@@ -128,13 +128,13 @@ describe('getChineseYearMonthDayInfo', () => {
         }
 
         const items = line.split('\t');
-        const gregorianDate = items[0];
+        const gregorianDate = items[0] as string;
         const gregorianDateItems = gregorianDate.split('/');
-        const gregorianYear = parseInt(gregorianDateItems[0]);
-        const gregorianMonth = parseInt(gregorianDateItems[1]);
-        const gregorianDay = parseInt(gregorianDateItems[2]);
-        const expectedChineseMonthOrDay = items[1];
-        const expectedSolarTermName = items.length > 3 ? items[3] : '';
+        const gregorianYear = parseInt(gregorianDateItems[0] as string);
+        const gregorianMonth = parseInt(gregorianDateItems[1] as string);
+        const gregorianDay = parseInt(gregorianDateItems[2] as string);
+        const expectedChineseMonthOrDay = items[1] as string;
+        const expectedSolarTermName = items.length > 3 ? items[3] as string : '';
 
         test(`returns correct chinese date for ${gregorianDate}`, () => {
             const actualChineseDate: ChineseYearMonthDayInfo | undefined = getChineseYearMonthDayInfo({
diff --git a/src/lib/calendar/chinese_calendar.ts b/src/lib/calendar/chinese_calendar.ts
index 00adf38a..446ed827 100644
--- a/src/lib/calendar/chinese_calendar.ts
+++ b/src/lib/calendar/chinese_calendar.ts
@@ -177,9 +177,9 @@ function getSolarTermName(gregorianDate: YearMonthDay, localeData: ChineseCalend
     const [firstTermDay, firstTermIndex, secondTermDay, secondTermIndex] = getSolarTermDays(gregorianDate.year, gregorianDate.month);
 
     if (firstTermDay > 0 && firstTermDay === gregorianDate.day) {
-        return localeData.solarTermNames[firstTermIndex];
+        return localeData.solarTermNames[firstTermIndex] ?? '';
     } else if (secondTermDay > 0 && secondTermDay === gregorianDate.day) {
-        return localeData.solarTermNames[secondTermIndex];
+        return localeData.solarTermNames[secondTermIndex] ?? '';
     } else {
         return '';
     }
@@ -317,7 +317,7 @@ function buildChineseYearMonthDayInfo(gregorianDate: YearMonthDay, chineseDate:
         day: chineseDate.day,
         displayYear: getChineseNumber(chineseDate.year, localeData),
         displayMonth: (chineseDate.isLeapMonth ? localeData.leapMonthPrefix : '') + localeData.monthNames[chineseDate.month - 1],
-        displayDay: localeData.dayNames[chineseDate.day - 1],
+        displayDay: localeData.dayNames[chineseDate.day - 1] ?? '',
         isLeapMonth: chineseDate.isLeapMonth,
         solarTermName: getSolarTermName(gregorianDate, localeData)
     };
diff --git a/src/lib/category.ts b/src/lib/category.ts
index bba36082..1ccf1aa2 100644
--- a/src/lib/category.ts
+++ b/src/lib/category.ts
@@ -1,3 +1,4 @@
+import { itemAndIndex, reversed, entries, keys, values } from '@/core/base.ts';
 import { type LocalizedPresetCategory, CategoryType } from '@/core/category.ts';
 import { TransactionType } from '@/core/transaction.ts';
 import {
@@ -34,8 +35,7 @@ export function categoryTypeToTransactionType(categoryType: CategoryType): Trans
 export function localizedPresetCategoryToTransactionCategoryCreateWithSubCategorys(presetCategory: LocalizedPresetCategory): TransactionCategoryCreateWithSubCategories {
     const subCategories: TransactionCategoryCreateRequest[] = [];
 
-    for (let i = 0; i < presetCategory.subCategories.length; i++) {
-        const subPresetCategory = presetCategory.subCategories[i];
+    for (const subPresetCategory of presetCategory.subCategories) {
         const subCategory: TransactionCategoryCreateRequest = {
             name: subPresetCategory.name,
             type: subPresetCategory.type,
@@ -63,8 +63,7 @@ export function localizedPresetCategoryToTransactionCategoryCreateWithSubCategor
 export function localizedPresetCategoriesToTransactionCategoryCreateWithSubCategories(presetCategories: LocalizedPresetCategory[]): TransactionCategoryCreateWithSubCategories[] {
     const categories: TransactionCategoryCreateWithSubCategories[] = [];
 
-    for (let i = 0; i < presetCategories.length; i++) {
-        const presetCategory = presetCategories[i];
+    for (const presetCategory of presetCategories) {
         const categoryWithSubCategories = localizedPresetCategoryToTransactionCategoryCreateWithSubCategorys(presetCategory);
         categories.push(categoryWithSubCategories);
     }
@@ -79,12 +78,9 @@ export function getSecondaryTransactionMapByName(allCategories: TransactionCateg
         return ret;
     }
 
-    for (let i = 0; i < allCategories.length; i++) {
-        const category = allCategories[i];
-
+    for (const category of allCategories) {
         if (category.subCategories) {
-            for (let j = 0; j < category.subCategories.length; j++) {
-                const subCategory = category.subCategories[j];
+            for (const subCategory of category.subCategories) {
                 ret[subCategory.name] = subCategory;
             }
         }
@@ -93,22 +89,21 @@ export function getSecondaryTransactionMapByName(allCategories: TransactionCateg
     return ret;
 }
 
-export function getTransactionPrimaryCategoryName(categoryId: string | null | undefined, allCategories: TransactionCategory[]): string {
+export function getTransactionPrimaryCategoryName(categoryId: string | null | undefined, allCategories?: TransactionCategory[]): string {
     if (!allCategories) {
         return '';
     }
 
-    for (let i = 0; i < allCategories.length; i++) {
-        const subCategoryList = allCategories[i].subCategories;
+    for (const category of allCategories) {
+        const subCategoryList = category.subCategories;
 
         if (!subCategoryList) {
             continue;
         }
 
-        for (let j = 0; j < subCategoryList.length; j++) {
-            const subCategory = subCategoryList[j];
+        for (const subCategory of subCategoryList) {
             if (subCategory.id === categoryId) {
-                return allCategories[i].name;
+                return category.name;
             }
         }
     }
@@ -116,20 +111,19 @@ export function getTransactionPrimaryCategoryName(categoryId: string | null | un
     return '';
 }
 
-export function getTransactionSecondaryCategoryName(categoryId: string | null | undefined, allCategories: TransactionCategory[]): string {
+export function getTransactionSecondaryCategoryName(categoryId: string | null | undefined, allCategories?: TransactionCategory[]): string {
     if (!allCategories) {
         return '';
     }
 
-    for (let i = 0; i < allCategories.length; i++) {
-        const subCategoryList = allCategories[i].subCategories;
+    for (const category of allCategories) {
+        const subCategoryList = category.subCategories;
 
         if (!subCategoryList) {
             continue;
         }
 
-        for (let j = 0; j < subCategoryList.length; j++) {
-            const subCategory = subCategoryList[j];
+        for (const subCategory of subCategoryList) {
             if (subCategory.id === categoryId) {
                 return subCategory.name;
             }
@@ -148,9 +142,7 @@ export function allTransactionCategoriesWithVisibleCount(allTransactionCategorie
 
     const allCategoryTypes = [ CategoryType.Income, CategoryType.Expense, CategoryType.Transfer ];
 
-    for (let i = 0; i < allCategoryTypes.length; i++) {
-        const categoryType = allCategoryTypes[i];
-
+    for (const categoryType of allCategoryTypes) {
         if (!allTransactionCategories[categoryType]) {
             continue;
         }
@@ -166,14 +158,12 @@ export function allTransactionCategoriesWithVisibleCount(allTransactionCategorie
         let allVisibleCategoryCount = 0;
         let firstVisibleCategoryIndex = -1;
 
-        for (let j = 0; j < allCategories.length; j++) {
-            const category = allCategories[j];
-
+        for (const [category, cagtegoryIndex] of itemAndIndex(allCategories)) {
             if (!category.hidden) {
                 allVisibleCategoryCount++;
 
                 if (firstVisibleCategoryIndex === -1) {
-                    firstVisibleCategoryIndex = j;
+                    firstVisibleCategoryIndex = cagtegoryIndex;
                 }
             }
 
@@ -181,14 +171,12 @@ export function allTransactionCategoriesWithVisibleCount(allTransactionCategorie
                 let visibleSubCategoryCount = 0;
                 let firstVisibleSubCategoryIndex = -1;
 
-                for (let k = 0; k < category.subCategories.length; k++) {
-                    const subCategory = category.subCategories[k];
-
+                for (const [subCategory, subCategoryIndex] of itemAndIndex(category.subCategories)) {
                     if (!subCategory.hidden) {
                         visibleSubCategoryCount++;
 
                         if (firstVisibleSubCategoryIndex === -1) {
-                            firstVisibleSubCategoryIndex = k;
+                            firstVisibleSubCategoryIndex = subCategoryIndex;
                         }
                     }
                 }
@@ -223,9 +211,7 @@ export function allVisiblePrimaryTransactionCategoriesByType(allTransactionCateg
         return visibleCategories;
     }
 
-    for (let i = 0; i < allCategories.length; i++) {
-        const category = allCategories[i];
-
+    for (const category of allCategories) {
         if (category.hidden) {
             continue;
         }
@@ -243,13 +229,7 @@ export function getFinalCategoryIdsByFilteredCategoryIds(allTransactionCategorie
         return finalCategoryIds;
     }
 
-    for (const categoryId in allTransactionCategoriesMap) {
-        if (!Object.prototype.hasOwnProperty.call(allTransactionCategoriesMap, categoryId)) {
-            continue;
-        }
-
-        const category = allTransactionCategoriesMap[categoryId];
-
+    for (const category of values(allTransactionCategoriesMap)) {
         if (filteredCategoryIds && !isCategoryOrSubCategoriesAllChecked(category, filteredCategoryIds)) {
             continue;
         }
@@ -269,9 +249,7 @@ export function isSubCategoryIdAvailable(categories: TransactionCategory[], cate
         return false;
     }
 
-    for (let i = 0; i < categories.length; i++) {
-        const primaryCategory = categories[i];
-
+    for (const primaryCategory of categories) {
         if (primaryCategory.hidden) {
             continue;
         }
@@ -282,9 +260,7 @@ export function isSubCategoryIdAvailable(categories: TransactionCategory[], cate
             continue;
         }
 
-        for (let j = 0; j < subCategoryList.length; j++) {
-            const secondaryCategory = subCategoryList[j];
-
+        for (const secondaryCategory of subCategoryList) {
             if (secondaryCategory.hidden) {
                 continue;
             }
@@ -303,9 +279,7 @@ export function getFirstAvailableCategoryId(categories: TransactionCategory[]):
         return '';
     }
 
-    for (let i = 0; i < categories.length; i++) {
-        const primaryCategory = categories[i];
-
+    for (const primaryCategory of categories) {
         if (primaryCategory.hidden) {
             continue;
         }
@@ -316,9 +290,7 @@ export function getFirstAvailableCategoryId(categories: TransactionCategory[]):
             continue;
         }
 
-        for (let j = 0; j < subCategoryList.length; j++) {
-            const secondaryCategory = subCategoryList[j];
-
+        for (const secondaryCategory of subCategoryList) {
             if (secondaryCategory.hidden) {
                 continue;
             }
@@ -335,9 +307,7 @@ export function getFirstAvailableSubCategoryId(categories: TransactionCategory[]
         return '';
     }
 
-    for (let i = 0; i < categories.length; i++) {
-        const primaryCategory = categories[i];
-
+    for (const primaryCategory of categories) {
         if (primaryCategory.hidden || primaryCategory.id !== categoryId) {
             continue;
         }
@@ -348,9 +318,7 @@ export function getFirstAvailableSubCategoryId(categories: TransactionCategory[]
             return '';
         }
 
-        for (let j = 0; j < subCategoryList.length; j++) {
-            const secondaryCategory = subCategoryList[j];
-
+        for (const secondaryCategory of subCategoryList) {
             if (secondaryCategory.hidden) {
                 continue;
             }
@@ -365,8 +333,8 @@ export function getFirstAvailableSubCategoryId(categories: TransactionCategory[]
 }
 
 export function isNoAvailableCategory(categories: TransactionCategory[], showHidden: boolean): boolean {
-    for (let i = 0; i < categories.length; i++) {
-        if (showHidden || !categories[i].hidden) {
+    for (const category of categories) {
+        if (showHidden || !category.hidden) {
             return false;
         }
     }
@@ -377,8 +345,8 @@ export function isNoAvailableCategory(categories: TransactionCategory[], showHid
 export function getAvailableCategoryCount(categories: TransactionCategory[], showHidden: boolean): number {
     let count = 0;
 
-    for (let i = 0; i < categories.length; i++) {
-        if (showHidden || !categories[i].hidden) {
+    for (const category of categories) {
+        if (showHidden || !category.hidden) {
             count++;
         }
     }
@@ -387,9 +355,9 @@ export function getAvailableCategoryCount(categories: TransactionCategory[], sho
 }
 
 export function getFirstShowingId(categories: TransactionCategory[], showHidden: boolean): string | null {
-    for (let i = 0; i < categories.length; i++) {
-        if (showHidden || !categories[i].hidden) {
-            return categories[i].id;
+    for (const category of categories) {
+        if (showHidden || !category.hidden) {
+            return category.id;
         }
     }
 
@@ -397,9 +365,9 @@ export function getFirstShowingId(categories: TransactionCategory[], showHidden:
 }
 
 export function getLastShowingId(categories: TransactionCategory[], showHidden: boolean): string | null {
-    for (let i = categories.length - 1; i >= 0; i--) {
-        if (showHidden || !categories[i].hidden) {
-            return categories[i].id;
+    for (const category of reversed(categories)) {
+        if (showHidden || !category.hidden) {
+            return category.id;
         }
     }
 
@@ -407,13 +375,7 @@ export function getLastShowingId(categories: TransactionCategory[], showHidden:
 }
 
 export function containsAnyAvailableCategory(allTransactionCategories: Record<number, TransactionCategoriesWithVisibleCount>, showHidden: boolean): boolean {
-    for (const type in allTransactionCategories) {
-        if (!Object.prototype.hasOwnProperty.call(allTransactionCategories, type)) {
-            continue;
-        }
-
-        const categoryType = allTransactionCategories[type];
-
+    for (const categoryType of values(allTransactionCategories)) {
         if (showHidden) {
             if (categoryType.allCategories && categoryType.allCategories.length > 0) {
                 return true;
@@ -431,13 +393,7 @@ export function containsAnyAvailableCategory(allTransactionCategories: Record<nu
 export function containsAvailableCategory(allTransactionCategories: Record<number, TransactionCategoriesWithVisibleCount>, showHidden: boolean): Record<number, boolean> {
     const result: Record<number, boolean> = {};
 
-    for (const type in allTransactionCategories) {
-        if (!Object.prototype.hasOwnProperty.call(allTransactionCategories, type)) {
-            continue;
-        }
-
-        const categoryType = allTransactionCategories[type];
-
+    for (const [type, categoryType] of entries(allTransactionCategories)) {
         if (showHidden) {
             result[type] = categoryType.allCategories && categoryType.allCategories.length > 0;
         } else {
@@ -448,23 +404,18 @@ export function containsAvailableCategory(allTransactionCategories: Record<numbe
     return result;
 }
 
-export function selectAllSubCategories(filterCategoryIds: Record<string, boolean>, category: TransactionCategory, value: boolean): void {
+export function selectAllSubCategories(filterCategoryIds: Record<string, boolean>, value: boolean, category?: TransactionCategory): void {
     if (!category || !category.subCategories || !category.subCategories.length) {
         return;
     }
 
-    for (let i = 0; i < category.subCategories.length; i++) {
-        const subCategory = category.subCategories[i];
+    for (const subCategory of category.subCategories) {
         filterCategoryIds[subCategory.id] = value;
     }
 }
 
 export function selectAll(filterCategoryIds: Record<string, boolean>, allTransactionCategoriesMap: Record<string, TransactionCategory>): void {
-    for (const categoryId in filterCategoryIds) {
-        if (!Object.prototype.hasOwnProperty.call(filterCategoryIds, categoryId)) {
-            continue;
-        }
-
+    for (const categoryId of keys(filterCategoryIds)) {
         const category = allTransactionCategoriesMap[categoryId];
 
         if (category) {
@@ -474,11 +425,7 @@ export function selectAll(filterCategoryIds: Record<string, boolean>, allTransac
 }
 
 export function selectNone(filterCategoryIds: Record<string, boolean>, allTransactionCategoriesMap: Record<string, TransactionCategory>): void {
-    for (const categoryId in filterCategoryIds) {
-        if (!Object.prototype.hasOwnProperty.call(filterCategoryIds, categoryId)) {
-            continue;
-        }
-
+    for (const categoryId of keys(filterCategoryIds)) {
         const category = allTransactionCategoriesMap[categoryId];
 
         if (category) {
@@ -488,11 +435,7 @@ export function selectNone(filterCategoryIds: Record<string, boolean>, allTransa
 }
 
 export function selectInvert(filterCategoryIds: Record<string, boolean>, allTransactionCategoriesMap: Record<string, TransactionCategory>): void {
-    for (const categoryId in filterCategoryIds) {
-        if (!Object.prototype.hasOwnProperty.call(filterCategoryIds, categoryId)) {
-            continue;
-        }
-
+    for (const categoryId of keys(filterCategoryIds)) {
         const category = allTransactionCategoriesMap[categoryId];
 
         if (category) {
@@ -506,8 +449,7 @@ export function isCategoryOrSubCategoriesAllChecked(category: TransactionCategor
         return !filterCategoryIds[category.id];
     }
 
-    for (let i = 0; i < category.subCategories.length; i++) {
-        const subCategory = category.subCategories[i];
+    for (const subCategory of category.subCategories) {
         if (filterCategoryIds[subCategory.id]) {
             return false;
         }
@@ -521,8 +463,7 @@ export function isSubCategoriesAllChecked(category: TransactionCategory, filterC
         return false;
     }
 
-    for (let i = 0; i < category.subCategories.length; i++) {
-        const subCategory = category.subCategories[i];
+    for (const subCategory of category.subCategories) {
         if (filterCategoryIds[subCategory.id]) {
             return false;
         }
@@ -538,8 +479,7 @@ export function isSubCategoriesHasButNotAllChecked(category: TransactionCategory
         return false;
     }
 
-    for (let i = 0; i < category.subCategories.length; i++) {
-        const subCategory = category.subCategories[i];
+    for (const subCategory of category.subCategories) {
         if (!filterCategoryIds[subCategory.id]) {
             checkedCount++;
         }
diff --git a/src/lib/common.ts b/src/lib/common.ts
index 6dbd435a..52b619fe 100644
--- a/src/lib/common.ts
+++ b/src/lib/common.ts
@@ -1,3 +1,4 @@
+import { keys, keysIfValueEquals, values } from '@/core/base.ts';
 import type { NameValue, TypeAndName, TypeAndDisplayName} from '@/core/base.ts';
 
 // eslint-disable-next-line @typescript-eslint/no-unsafe-function-type
@@ -48,7 +49,7 @@ export function isYearMonth(val: unknown): val is string {
         return false;
     }
 
-    return !!parseInt(items[0]) && !!parseInt(items[1]);
+    return !!parseInt(items[0] as string) && !!parseInt(items[1] as string);
 }
 
 export function isEquals(obj1: unknown, obj2: unknown): boolean {
@@ -82,13 +83,13 @@ export function isEquals(obj1: unknown, obj2: unknown): boolean {
         const keyExistsMap2 = new Map<string, boolean>();
 
         for (let i = 0; i < keys2.length; i++) {
-            const key = keys2[i];
+            const key = keys2[i] as string;
 
             keyExistsMap2.set(key, true);
         }
 
         for (let i = 0; i < keys1.length; i++) {
-            const key = keys1[i];
+            const key = keys1[i] as string;
 
             if (!keyExistsMap2.get(key)) {
                 return false;
@@ -117,7 +118,7 @@ export function isYearMonthEquals(val1: unknown, val2: unknown): boolean {
         return false;
     }
 
-    return (!!parseInt(items1[0]) && !!parseInt(items1[1])) && (parseInt(items1[0]) === parseInt(items2[0])) && (parseInt(items1[1]) === parseInt(items2[1]));
+    return (!!parseInt(items1[0] as string) && !!parseInt(items1[1] as string)) && (parseInt(items1[0] as string) === parseInt(items2[0] as string)) && (parseInt(items1[1] as string) === parseInt(items2[1] as string));
 }
 
 export function isArray1SubsetOfArray2<T>(array1: T[], array2: T[]): boolean {
@@ -128,11 +129,11 @@ export function isArray1SubsetOfArray2<T>(array1: T[], array2: T[]): boolean {
     const array2ValuesMap: Map<T, boolean> = new Map<T, boolean>();
 
     for (let i = 0; i < array2.length; i++) {
-        array2ValuesMap.set(array2[i], true);
+        array2ValuesMap.set(array2[i] as T, true);
     }
 
     for (let i = 0; i < array1.length; i++) {
-        if (!array2ValuesMap.get(array1[i])) {
+        if (!array2ValuesMap.get(array1[i] as T)) {
             return false;
         }
     }
@@ -145,11 +146,7 @@ export function isObjectEmpty(obj: object): boolean {
         return true;
     }
 
-    for (const field in obj) {
-        if (!Object.prototype.hasOwnProperty.call(obj, field)) {
-            continue;
-        }
-
+    for (const _ of keys(obj)) {
         return false;
     }
 
@@ -183,11 +180,8 @@ export function getObjectOwnFieldCount(object: object): number {
         return count;
     }
 
-    for (const field in object) {
-        if (!Object.prototype.hasOwnProperty.call(object, field)) {
-            continue;
-        }
-
+    // eslint-disable-next-line @typescript-eslint/no-unused-vars
+    for (const _ of keys(object)) {
         count++;
     }
 
@@ -251,26 +245,22 @@ export function getFirstVisibleItem<T>(items: Record<string, T>[] | Record<strin
     if (isArray(items) && items.length > 0) {
         const arr = items as Record<string, T>[];
 
-        for (let i = 0; i < arr.length; i++) {
-            if (hiddenField && arr[i][hiddenField]) {
+        for (const item of arr) {
+            if (hiddenField && item[hiddenField]) {
                 continue;
             }
 
-            return arr[i];
+            return item;
         }
     } else if (isObject(items)) {
         const obj = items as Record<string, Record<string, T>>;
 
-        for (const field in obj) {
-            if (!Object.prototype.hasOwnProperty.call(obj, field)) {
+        for (const item of values(obj)) {
+            if (hiddenField && item[hiddenField]) {
                 continue;
             }
 
-            if (hiddenField && obj[field][hiddenField]) {
-                continue;
-            }
-
-            return obj[field];
+            return item;
         }
     }
 
@@ -281,9 +271,7 @@ export function getItemByKeyValue<T>(src: Record<string, T>[] | Record<string, R
     if (isArray(src)) {
         const arr = src as Record<string, T>[];
 
-        for (let i = 0; i < arr.length; i++) {
-            const item = arr[i];
-
+        for (const item of arr) {
             if (item[keyField] === value) {
                 return item;
             }
@@ -291,13 +279,7 @@ export function getItemByKeyValue<T>(src: Record<string, T>[] | Record<string, R
     } else if (isObject(src)) {
         const obj = src as Record<string, Record<string, T>>;
 
-        for (const field in obj) {
-            if (!Object.prototype.hasOwnProperty.call(src, field)) {
-                continue;
-            }
-
-            const item = obj[field];
-
+        for (const item of values(obj)) {
             if (item[keyField] === value) {
                 return item;
             }
@@ -342,9 +324,7 @@ export function getNameByKeyValue<V, N>(src: Record<string, N | V>[] | Record<st
         const arr = src as Record<string, N | V>[];
 
         if (keyField) {
-            for (let i = 0; i < arr.length; i++) {
-                const option = arr[i];
-
+            for (const option of arr) {
                 if (option[keyField] === value) {
                     return option[nameField] as N;
                 }
@@ -362,13 +342,7 @@ export function getNameByKeyValue<V, N>(src: Record<string, N | V>[] | Record<st
         const obj = src as Record<string, Record<string, N | V>>;
 
         if (keyField) {
-            for (const key in obj) {
-                if (!Object.prototype.hasOwnProperty.call(src, key)) {
-                    continue;
-                }
-
-                const option = obj[key];
-
+            for (const option of values(obj)) {
                 if (option[keyField] === value) {
                     return option[nameField] as N;
                 }
@@ -392,8 +366,8 @@ export function arrayContainsFieldValue<T>(array: Record<string, T>[], fieldName
         return false;
     }
 
-    for (let i = 0; i < array.length; i++) {
-        if (array[i][fieldName] === value) {
+    for (const item of array) {
+        if (item[fieldName] === value) {
             return true;
         }
     }
@@ -404,11 +378,7 @@ export function arrayContainsFieldValue<T>(array: Record<string, T>[], fieldName
 export function objectFieldToArrayItem(object: object): string[] {
     const ret: string[] = [];
 
-    for (const field in object) {
-        if (!Object.prototype.hasOwnProperty.call(object, field)) {
-            continue;
-        }
-
+    for (const field of keys(object)) {
         ret.push(field);
     }
 
@@ -418,14 +388,8 @@ export function objectFieldToArrayItem(object: object): string[] {
 export function objectFieldWithValueToArrayItem<T>(object: Record<string, T>, value: T): string[] {
     const ret: string[] = [];
 
-    for (const field in object) {
-        if (!Object.prototype.hasOwnProperty.call(object, field)) {
-            continue;
-        }
-
-        if (object[field] === value) {
-            ret.push(field);
-        }
+    for (const field of keysIfValueEquals(object, value)) {
+        ret.push(field);
     }
 
     return ret;
@@ -434,8 +398,8 @@ export function objectFieldWithValueToArrayItem<T>(object: Record<string, T>, va
 export function arrayItemToObjectField<T>(array: string[], value: T): Record<string, T> {
     const ret: Record<string, T> = {};
 
-    for (let i = 0; i < array.length; i++) {
-        ret[array[i]] = value;
+    for (const item of array) {
+        ret[item] = value;
     }
 
     return ret;
@@ -450,9 +414,9 @@ export function splitItemsToMap(str: string | undefined | null, separator: strin
 
     const items = str.split(separator);
 
-    for (let i = 0; i < items.length; i++) {
-        if (items[i]) {
-            ret[items[i]] = true;
+    for (const item of items) {
+        if (item) {
+            ret[item] = true;
         }
     }
 
@@ -479,15 +443,9 @@ export function countSplitItems(str: string | undefined | null, separator: strin
 export function categorizedArrayToPlainArray<T>(object: Record<string, T[]>): T[] {
     const ret: T[] = [];
 
-    for (const field in object) {
-        if (!Object.prototype.hasOwnProperty.call(object, field)) {
-            continue;
-        }
-
-        const array = object[field];
-
-        for (let i = 0; i < array.length; i++) {
-            ret.push(array[i]);
+    for (const array of values(object)) {
+        for (const item of array) {
+            ret.push(item);
         }
     }
 
@@ -495,11 +453,7 @@ export function categorizedArrayToPlainArray<T>(object: Record<string, T[]>): T[
 }
 
 export function selectAll(filterItemIds: Record<string, boolean>, allItemsMap: { [key: string]: { id: string } }): void {
-    for (const itemId in filterItemIds) {
-        if (!Object.prototype.hasOwnProperty.call(filterItemIds, itemId)) {
-            continue;
-        }
-
+    for (const itemId of keys(filterItemIds)) {
         const item = allItemsMap[itemId];
 
         if (item) {
@@ -509,11 +463,7 @@ export function selectAll(filterItemIds: Record<string, boolean>, allItemsMap: {
 }
 
 export function selectNone(filterItemIds: Record<string, boolean>, allItemsMap: { [key: string]: { id: string } }): void {
-    for (const itemId in filterItemIds) {
-        if (!Object.prototype.hasOwnProperty.call(filterItemIds, itemId)) {
-            continue;
-        }
-
+    for (const itemId of keys(filterItemIds)) {
         const item = allItemsMap[itemId];
 
         if (item) {
@@ -523,11 +473,7 @@ export function selectNone(filterItemIds: Record<string, boolean>, allItemsMap:
 }
 
 export function selectInvert(filterItemIds: Record<string, boolean>, allItemsMap: { [key: string]: { id: string } }): void {
-    for (const itemId in filterItemIds) {
-        if (!Object.prototype.hasOwnProperty.call(filterItemIds, itemId)) {
-            continue;
-        }
-
+    for (const itemId of keys(filterItemIds)) {
         const item = allItemsMap[itemId];
 
         if (item) {
@@ -610,11 +556,11 @@ export function arrangeArrayWithNewStartIndex<T>(array: T[], startIndex: number)
     const newArray: T[] = [];
 
     for (let i = startIndex; i < array.length; i++) {
-        newArray.push(array[i]);
+        newArray.push(array[i] as T);
     }
 
     for (let i = 0; i < startIndex; i++) {
-        newArray.push(array[i]);
+        newArray.push(array[i] as T);
     }
 
     return newArray;
diff --git a/src/lib/datetime.ts b/src/lib/datetime.ts
index 922c3c31..1cb83075 100644
--- a/src/lib/datetime.ts
+++ b/src/lib/datetime.ts
@@ -3,6 +3,9 @@ import { type unitOfTime } from 'moment/moment';
 
 import jalaali, { type JalaaliDateObject } from 'jalaali-js';
 
+import {
+    itemAndIndex
+} from '@/core/base.ts';
 import {
     type ChineseCalendarLocaleData,
     CalendarType
@@ -426,8 +429,8 @@ export function getYear0BasedMonthObjectFromString(yearMonth: TextualYearMonth |
         return null;
     }
 
-    const year = parseInt(items[0]);
-    const month0base = parseInt(items[1]) - 1;
+    const year = parseInt(items[0] as string);
+    const month0base = parseInt(items[1] as string) - 1;
 
     if (!isYear0BasedMonthValid(year, month0base)) {
         return null;
@@ -581,9 +584,9 @@ export function getLocalDateFromYearDashMonthDashDay(date: TextualYearMonthDay):
         return null;
     }
 
-    const year = parseInt(items[0]);
-    const month = parseInt(items[1]);
-    const day = parseInt(items[2]);
+    const year = parseInt(items[0] as string);
+    const month = parseInt(items[1] as string);
+    const day = parseInt(items[2] as string);
 
     if (!isNumber(year) || !isNumber(month) || !isNumber(day)) {
         return null;
@@ -983,8 +986,8 @@ export function getAllDaysStartAndEndUnixTimes(startUnixTime: number, endUnixTim
 }
 
 export function getDateTimeFormatType<T extends DateFormat | TimeFormat>(allFormatMap: Record<string, T>, allFormatArray: T[], formatTypeValue: number, languageDefaultTypeName: string, systemDefaultFormatType: T): T {
-    if (formatTypeValue > LANGUAGE_DEFAULT_DATE_TIME_FORMAT_VALUE && allFormatArray[formatTypeValue - 1] && allFormatArray[formatTypeValue - 1].key) {
-        return allFormatArray[formatTypeValue - 1];
+    if (formatTypeValue > LANGUAGE_DEFAULT_DATE_TIME_FORMAT_VALUE && allFormatArray[formatTypeValue - 1] && allFormatArray[formatTypeValue - 1]!.key) {
+        return allFormatArray[formatTypeValue - 1] as T;
     } else if (formatTypeValue === LANGUAGE_DEFAULT_DATE_TIME_FORMAT_VALUE && allFormatMap[languageDefaultTypeName] && allFormatMap[languageDefaultTypeName].key) {
         return allFormatMap[languageDefaultTypeName];
     } else {
@@ -1079,9 +1082,7 @@ export function getDateTypeByDateRange(minTime: number, maxTime: number, firstDa
     const allDateRanges = DateRange.values();
     let newDateType = DateRange.Custom.type;
 
-    for (let i = 0; i < allDateRanges.length; i++) {
-        const dateRange = allDateRanges[i];
-
+    for (const dateRange of allDateRanges) {
         if (!dateRange.isAvailableForScene(scene)) {
             continue;
         }
@@ -1264,9 +1265,9 @@ export function getRecentMonthDateRanges(monthCount: number): RecentMonthDateRan
 }
 
 export function getRecentDateRangeIndexByDateType(allRecentMonthDateRanges: LocalizedRecentMonthDateRange[], dateType: number): number {
-    for (let i = 0; i < allRecentMonthDateRanges.length; i++) {
-        if (!allRecentMonthDateRanges[i].isPreset && allRecentMonthDateRanges[i].dateType === dateType) {
-            return i;
+    for (const [recentDateRange, index] of itemAndIndex(allRecentMonthDateRanges)) {
+        if (!recentDateRange.isPreset && recentDateRange.dateType === dateType) {
+            return index;
         }
     }
 
@@ -1292,11 +1293,9 @@ export function getRecentDateRangeIndex(allRecentMonthDateRanges: LocalizedRecen
         };
     }
 
-    for (let i = 0; i < allRecentMonthDateRanges.length; i++) {
-        const recentDateRange = allRecentMonthDateRanges[i];
-
+    for (const [recentDateRange, index] of itemAndIndex(allRecentMonthDateRanges)) {
         if (recentDateRange.isPreset && recentDateRange.minTime === dateRange.minTime && recentDateRange.maxTime === dateRange.maxTime) {
-            return i;
+            return index;
         }
     }
 
@@ -1356,7 +1355,7 @@ export function getValidMonthDayOrCurrentDayShortDate(unixTime: number, currentS
         const yearMonthDay = currentShortDate.split('-');
 
         if (yearMonthDay.length === 3) {
-            const currentDay = parseInt(yearMonthDay[2]);
+            const currentDay = parseInt(yearMonthDay[2] as string);
 
             if (currentDay < monthLastTime.date()) {
                 return MomentDateTime.of(monthLastTime.set({ date: currentDay })).getGregorianCalendarYearDashMonthDashDay();
diff --git a/src/lib/file.ts b/src/lib/file.ts
index f7b149a1..e680914d 100644
--- a/src/lib/file.ts
+++ b/src/lib/file.ts
@@ -8,7 +8,7 @@ export function getFileExtension(filename: string): string {
     }
 
     const parts = filename.split('.');
-    return parts[parts.length - 1];
+    return parts[parts.length - 1] as string;
 }
 
 export function findExtensionByType(items: ImportFileTypeAndExtensions[] | undefined, type: string): string | undefined {
@@ -33,10 +33,8 @@ export function isFileExtensionSupported(filename: string, supportedExtensions:
     const supportedExtensionsArray = supportedExtensions.split(',');
     const fileExtension = getFileExtension(filename).toLowerCase();
 
-    for (let i = 0; i < supportedExtensionsArray.length; i++) {
-        const supportedExtension = getFileExtension(supportedExtensionsArray[i]).toLowerCase();
-
-        if (supportedExtension === fileExtension) {
+    for (const supportedExtension of supportedExtensionsArray) {
+        if (getFileExtension(supportedExtension).toLowerCase() === fileExtension) {
             return true;
         }
     }
diff --git a/src/lib/icon.ts b/src/lib/icon.ts
index 8c489d6d..6e98651b 100644
--- a/src/lib/icon.ts
+++ b/src/lib/icon.ts
@@ -1,24 +1,19 @@
+import { entries } from '@/core/base.ts';
 import type { IconInfo, IconInfoWithId } from '@/core/icon.ts';
 
 export function getIconsInRows(allIconInfos: Record<string, IconInfo>, itemPerRow: number): IconInfoWithId[][] {
     const ret: IconInfoWithId[][] = [];
     let rowCount = 0;
 
-    for (const iconInfoId in allIconInfos) {
-        if (!Object.prototype.hasOwnProperty.call(allIconInfos, iconInfoId)) {
-            continue;
-        }
-
-        const iconInfo = allIconInfos[iconInfoId];
-
+    for (const [iconInfoId, iconInfo] of entries(allIconInfos)) {
         if (!ret[rowCount]) {
             ret[rowCount] = [];
-        } else if (ret[rowCount] && ret[rowCount].length >= itemPerRow) {
+        } else if (ret[rowCount] && ret[rowCount]!.length >= itemPerRow) {
             rowCount++;
             ret[rowCount] = [];
         }
 
-        ret[rowCount].push({
+        ret[rowCount]!.push({
             id: iconInfoId,
             icon: iconInfo.icon
         });
diff --git a/src/lib/statistics.ts b/src/lib/statistics.ts
index 82b95757..a53a8ead 100644
--- a/src/lib/statistics.ts
+++ b/src/lib/statistics.ts
@@ -18,7 +18,7 @@ export function sortStatisticsItems<T extends SortableTransactionStatisticDataIt
         items.sort(function (data1, data2) {
             for (let i = 0; i < Math.min(data1.displayOrders.length, data2.displayOrders.length); i++) {
                 if (data1.displayOrders[i] !== data2.displayOrders[i]) {
-                    return data1.displayOrders[i] - data2.displayOrders[i]; // asc
+                    return (data1.displayOrders[i] as number) - (data2.displayOrders[i] as number); // asc
                 }
             }
 
@@ -52,12 +52,8 @@ export function getAllDateRangesFromItems<T extends Year1BasedMonth>(items: Year
     if ((!startYearMonth || !endYearMonth) && items && items.length) {
         let minYear = Number.MAX_SAFE_INTEGER, minMonth = Number.MAX_SAFE_INTEGER, maxYear = 0, maxMonth = 0;
 
-        for (let i = 0; i < items.length; i++) {
-            const item = items[i];
-
-            for (let j = 0; j < item.items.length; j++) {
-                const dataItem = item.items[j];
-
+        for (const item of items) {
+            for (const dataItem of item.items) {
                 if (dataItem.year < minYear || (dataItem.year === minYear && dataItem.month1base < minMonth)) {
                     minYear = dataItem.year;
                     minMonth = dataItem.month1base;
diff --git a/src/lib/ui/common.ts b/src/lib/ui/common.ts
index 7479a9c7..4f4d5841 100644
--- a/src/lib/ui/common.ts
+++ b/src/lib/ui/common.ts
@@ -59,9 +59,7 @@ export function setExpenseAndIncomeAmountColor(expenseAmountColorType: number, i
 
     const allPresetAmountColors = PresetAmountColor.values();
 
-    for (let i = 0; i < allPresetAmountColors.length; i++) {
-        const amountColor = allPresetAmountColors[i];
-
+    for (const amountColor of allPresetAmountColors) {
         if (amountColor.type === expenseAmountColor.type) {
             if (!htmlElement.classList.contains(amountColor.expenseClassName)) {
                 htmlElement.classList.add(amountColor.expenseClassName);
@@ -97,8 +95,8 @@ export function openTextFileContent({ allowedExtensions }: { allowedExtensions:
         fileInput.onchange = (event) => {
             const el = event.target as HTMLInputElement;
 
-            if (el.files && el.files.length > 0) {
-                const file = el.files[0];
+            if (el.files && el.files.length > 0 && el.files[0]) {
+                const file = el.files[0] as File;
                 const reader = new FileReader();
 
                 reader.onload = (e) => {
@@ -146,8 +144,7 @@ export function clearBrowserCaches(): Promise<void> {
         window.caches.keys().then(cacheNames => {
             const promises = [];
 
-            for (let i = 0; i < cacheNames.length; i++) {
-                const cacheName = cacheNames[i];
+            for (const cacheName of cacheNames) {
                 promises.push(window.caches.delete(cacheName).then(success => {
                     if (success) {
                         logger.info(`cache "${cacheName}" cleared successfully`);
diff --git a/src/lib/ui/mobile.ts b/src/lib/ui/mobile.ts
index 274a2654..d9e22613 100644
--- a/src/lib/ui/mobile.ts
+++ b/src/lib/ui/mobile.ts
@@ -74,9 +74,7 @@ export function setAppFontSize(type: number): void {
     const htmlElement = f7.$('html');
     const allFontSizes = FontSize.values();
 
-    for (let i = 0; i < allFontSizes.length; i++) {
-        const fontSizeType = allFontSizes[i];
-
+    for (const fontSizeType of allFontSizes) {
         if (fontSizeType.type === type) {
             if (!htmlElement.hasClass(fontSizeType.className)) {
                 htmlElement.addClass(fontSizeType.className);
@@ -90,9 +88,7 @@ export function setAppFontSize(type: number): void {
 export function getFontSizePreviewClassName(type: number): string {
     const allFontSizes = FontSize.values();
 
-    for (let i = 0; i < allFontSizes.length; i++) {
-        const fontSizeType = allFontSizes[i];
-
+    for (const fontSizeType of allFontSizes) {
         if (fontSizeType.type === type) {
             return FONT_SIZE_PREVIEW_CLASSNAME_PREFIX + fontSizeType.className;
         }
@@ -109,8 +105,7 @@ export function getElementActualHeights(selector: string): Record<string, number
         return heights;
     }
 
-    for (let i = 0; i < elements.length; i++) {
-        const el = elements[i];
+    for (const el of elements) {
         const rect = el.getBoundingClientRect();
         heights[el.id] = rect.height;
     }
diff --git a/src/lib/webauthn.ts b/src/lib/webauthn.ts
index c583edb8..85662dcb 100644
--- a/src/lib/webauthn.ts
+++ b/src/lib/webauthn.ts
@@ -180,7 +180,7 @@ export function verifyWebAuthnCredential(userInfo: UserBasicInfo, credentialId:
     }) as PublicKeyCredentialRequestOptions;
 
     if (publicKeyCredentialRequestOptions.allowCredentials && publicKeyCredentialRequestOptions.allowCredentials.length > 0) {
-        publicKeyCredentialRequestOptions.allowCredentials[0].id = stringToArrayBuffer(base64decode(credentialId));
+        publicKeyCredentialRequestOptions.allowCredentials[0]!.id = stringToArrayBuffer(base64decode(credentialId));
     }
 
     logger.debug('webauthn get options', publicKeyCredentialRequestOptions);
@@ -199,8 +199,8 @@ export function verifyWebAuthnCredential(userInfo: UserBasicInfo, credentialId:
             userIdParts && userIdParts.length === 2 && userIdParts[0] === userInfo.username) {
             const ret: WebAuthnVerifyResponse = {
                 id: base64encode(rawCredential.rawId),
-                userName: userIdParts[0],
-                userSecret: userIdParts[1],
+                userName: userIdParts[0] as string,
+                userSecret: userIdParts[1] as string,
                 clientData: clientData,
                 rawCredential: rawCredential
             };
diff --git a/src/stores/overview.ts b/src/stores/overview.ts
index 7d3f1487..6557681e 100644
--- a/src/stores/overview.ts
+++ b/src/stores/overview.ts
@@ -156,9 +156,7 @@ export const useOverviewStore = defineStore('overview', () => {
             let hasUnCalculatedTotalExpense = false;
 
             if (item.amounts) {
-                for (let i = 0; i < item.amounts.length; i++) {
-                    const amount = item.amounts[i];
-
+                for (const amount of item.amounts) {
                     if (amount.currency !== defaultCurrency) {
                         const incomeAmount = exchangeRatesStore.getExchangedAmount(amount.incomeAmount, amount.currency, defaultCurrency);
                         const expenseAmount = exchangeRatesStore.getExchangedAmount(amount.expenseAmount, amount.currency, defaultCurrency);
diff --git a/src/views/base/ExchangeRatesPageBase.ts b/src/views/base/ExchangeRatesPageBase.ts
index 9ca87106..641d69c2 100644
--- a/src/views/base/ExchangeRatesPageBase.ts
+++ b/src/views/base/ExchangeRatesPageBase.ts
@@ -35,7 +35,7 @@ export function useExchangeRatesPageBase() {
         return getAllDisplayExchangeRates(exchangeRatesData.value);
     });
 
-    function getConvertedAmount(baseAmount: number | '', fromExchangeRate: LatestExchangeRate | LocalizedLatestExchangeRate, toExchangeRate: LatestExchangeRate | LocalizedLatestExchangeRate): number | '' | null {
+    function getConvertedAmount(baseAmount: number | '', fromExchangeRate?: LatestExchangeRate | LocalizedLatestExchangeRate, toExchangeRate?: LatestExchangeRate | LocalizedLatestExchangeRate): number | '' | null {
         if (!fromExchangeRate || !toExchangeRate) {
             return '';
         }
diff --git a/src/views/base/accounts/AccountEditPageBase.ts b/src/views/base/accounts/AccountEditPageBase.ts
index e96ddc99..d38fa9ba 100644
--- a/src/views/base/accounts/AccountEditPageBase.ts
+++ b/src/views/base/accounts/AccountEditPageBase.ts
@@ -52,8 +52,8 @@ export function useAccountEditPageBaseBase() {
         }
 
         if (account.value.type === AccountType.MultiSubAccounts.type) {
-            for (let i = 0; i < subAccounts.value.length; i++) {
-                problemMessage = getInputEmptyProblemMessage(subAccounts.value[i], true);
+            for (const subAccount of subAccounts.value) {
+                problemMessage = getInputEmptyProblemMessage(subAccount, true);
 
                 if (problemMessage) {
                     return problemMessage;
@@ -132,9 +132,9 @@ export function useAccountEditPageBaseBase() {
         subAccounts.value = [];
 
         if (newAccount.subAccounts && newAccount.subAccounts.length > 0) {
-            for (let i = 0; i < newAccount.subAccounts.length; i++) {
+            for (const oldSubAccount of newAccount.subAccounts) {
                 const subAccount: Account = account.value.createNewSubAccount(userStore.currentUserDefaultCurrency, getCurrentUnixTime());
-                subAccount.fillFrom(newAccount.subAccounts[i]);
+                subAccount.fillFrom(oldSubAccount);
 
                 subAccounts.value.push(subAccount);
             }
diff --git a/src/views/base/accounts/ReconciliationStatementPageBase.ts b/src/views/base/accounts/ReconciliationStatementPageBase.ts
index 44435639..df1359ac 100644
--- a/src/views/base/accounts/ReconciliationStatementPageBase.ts
+++ b/src/views/base/accounts/ReconciliationStatementPageBase.ts
@@ -150,7 +150,7 @@ export function useReconciliationStatementPageBase() {
         let currency = defaultCurrency.value;
 
         if (allAccountsMap.value[transaction.sourceAccountId]) {
-            currency = allAccountsMap.value[transaction.sourceAccountId].currency;
+            currency = allAccountsMap.value[transaction.sourceAccountId]!.currency;
         }
 
         return formatAmountToLocalizedNumeralsWithCurrency(transaction.sourceAmount, currency);
@@ -160,7 +160,7 @@ export function useReconciliationStatementPageBase() {
         let currency = defaultCurrency.value;
 
         if (allAccountsMap.value[transaction.destinationAccountId]) {
-            currency = allAccountsMap.value[transaction.destinationAccountId].currency;
+            currency = allAccountsMap.value[transaction.destinationAccountId]!.currency;
         }
 
         return formatAmountToLocalizedNumeralsWithCurrency(transaction.destinationAmount, currency);
@@ -172,12 +172,12 @@ export function useReconciliationStatementPageBase() {
 
         if (transaction.type === TransactionType.Transfer && transaction.destinationAccountId === accountId.value) {
             if (allAccountsMap.value[transaction.destinationAccountId]) {
-                currency = allAccountsMap.value[transaction.destinationAccountId].currency;
-                isLiabilityAccount = allAccountsMap.value[transaction.destinationAccountId].isLiability;
+                currency = allAccountsMap.value[transaction.destinationAccountId]!.currency;
+                isLiabilityAccount = allAccountsMap.value[transaction.destinationAccountId]!.isLiability;
             }
         } else if (allAccountsMap.value[transaction.sourceAccountId]) {
-            currency = allAccountsMap.value[transaction.sourceAccountId].currency;
-            isLiabilityAccount = allAccountsMap.value[transaction.sourceAccountId].isLiability;
+            currency = allAccountsMap.value[transaction.sourceAccountId]!.currency;
+            isLiabilityAccount = allAccountsMap.value[transaction.sourceAccountId]!.isLiability;
         }
 
         if (isLiabilityAccount) {
diff --git a/src/views/base/settings/CategoryFilterSettingPageBase.ts b/src/views/base/settings/CategoryFilterSettingPageBase.ts
index 180dedf5..1293ca19 100644
--- a/src/views/base/settings/CategoryFilterSettingPageBase.ts
+++ b/src/views/base/settings/CategoryFilterSettingPageBase.ts
@@ -8,6 +8,7 @@ import { useTransactionsStore } from '@/stores/transaction.ts';
 import { useStatisticsStore } from '@/stores/statistics.ts';
 import { useOverviewStore } from '@/stores/overview.ts';
 
+import { keys, keysIfValueEquals, values } from '@/core/base.ts';
 import { CategoryType } from '@/core/category.ts';
 import type { TransactionCategory, TransactionCategoriesWithVisibleCount } from '@/models/transaction_category.ts';
 
@@ -80,13 +81,7 @@ export function useCategoryFilterSettingPageBase(type?: CategoryFilterType, allo
     function loadFilterCategoryIds(): boolean {
         const allCategoryIds: Record<string, boolean> = {};
 
-        for (const categoryId in transactionCategoriesStore.allTransactionCategoriesMap) {
-            if (!Object.prototype.hasOwnProperty.call(transactionCategoriesStore.allTransactionCategoriesMap, categoryId)) {
-                continue;
-            }
-
-            const category = transactionCategoriesStore.allTransactionCategoriesMap[categoryId];
-
+        for (const category of values(transactionCategoriesStore.allTransactionCategoriesMap)) {
             if (allowCategoryTypes && !allowCategoryTypes[category.type]) {
                 continue;
             }
@@ -108,17 +103,13 @@ export function useCategoryFilterSettingPageBase(type?: CategoryFilterType, allo
             filterCategoryIds.value = Object.assign(allCategoryIds, settingsStore.appSettings.overviewTransactionCategoryFilterInHomePage);
             return true;
         } else if (type === 'transactionListCurrent') {
-            for (const categoryId in transactionsStore.allFilterCategoryIds) {
-                if (!Object.prototype.hasOwnProperty.call(transactionsStore.allFilterCategoryIds, categoryId)) {
-                    continue;
-                }
-
+            for (const categoryId of keysIfValueEquals(transactionsStore.allFilterCategoryIds, true)) {
                 const category = transactionCategoriesStore.allTransactionCategoriesMap[categoryId];
 
                 if (category && (!category.subCategories || !category.subCategories.length)) {
                     allCategoryIds[category.id] = false;
                 } else if (category) {
-                    selectAllSubCategories(allCategoryIds, category, false);
+                    selectAllSubCategories(allCategoryIds, false, category);
                 }
             }
 
@@ -135,11 +126,7 @@ export function useCategoryFilterSettingPageBase(type?: CategoryFilterType, allo
         let finalCategoryIds = '';
         let changed = true;
 
-        for (const categoryId in filterCategoryIds.value) {
-            if (!Object.prototype.hasOwnProperty.call(filterCategoryIds.value, categoryId)) {
-                continue;
-            }
-
+        for (const categoryId of keys(filterCategoryIds.value)) {
             const category = transactionCategoriesStore.allTransactionCategoriesMap[categoryId];
 
             if (!category) {
diff --git a/src/views/base/transactions/TransactionEditPageBase.ts b/src/views/base/transactions/TransactionEditPageBase.ts
index 64c1b058..aead3a49 100644
--- a/src/views/base/transactions/TransactionEditPageBase.ts
+++ b/src/views/base/transactions/TransactionEditPageBase.ts
@@ -396,9 +396,9 @@ export function useTransactionEditPageBase(type: TransactionEditPageType, initMo
     });
 
     watch(() => transaction.value.timeZone, (newValue) => {
-        for (let i = 0; i < allTimezones.value.length; i++) {
-            if (allTimezones.value[i].name === newValue) {
-                transaction.value.utcOffset = allTimezones.value[i].utcOffsetMinutes;
+        for (const timezone of allTimezones.value) {
+            if (timezone.name === newValue) {
+                transaction.value.utcOffset = timezone.utcOffsetMinutes;
                 break;
             }
         }
diff --git a/src/views/desktop/accounts/list/dialogs/EditDialog.vue b/src/views/desktop/accounts/list/dialogs/EditDialog.vue
index 33e1f92b..f314905a 100644
--- a/src/views/desktop/accounts/list/dialogs/EditDialog.vue
+++ b/src/views/desktop/accounts/list/dialogs/EditDialog.vue
@@ -260,7 +260,7 @@ const selectedAccount = computed<Account>(() => {
         return account.value;
     }
 
-    return subAccounts.value[currentAccountIndex.value];
+    return subAccounts.value[currentAccountIndex.value] as Account;
 });
 
 const accountAmountTitle = computed<string>(() => {
diff --git a/src/views/desktop/common/cards/CategoryFilterSettingsCard.vue b/src/views/desktop/common/cards/CategoryFilterSettingsCard.vue
index 0bf65431..c1cd23f0 100644
--- a/src/views/desktop/common/cards/CategoryFilterSettingsCard.vue
+++ b/src/views/desktop/common/cards/CategoryFilterSettingsCard.vue
@@ -248,7 +248,7 @@ function updateCategorySelected(category: TransactionCategory, value: boolean |
 }
 
 function updateAllSubCategoriesSelected(category: TransactionCategory, value: boolean | null): void {
-    selectAllSubCategories(filterCategoryIds.value, category, !value);
+    selectAllSubCategories(filterCategoryIds.value, !value, category);
 
     if (props.autoSave) {
         save();
diff --git a/src/views/desktop/transactions/import/ImportDialog.vue b/src/views/desktop/transactions/import/ImportDialog.vue
index d4734f7b..af1a7712 100644
--- a/src/views/desktop/transactions/import/ImportDialog.vue
+++ b/src/views/desktop/transactions/import/ImportDialog.vue
@@ -1888,11 +1888,11 @@ function setImportFile(event: Event): void {
 
     const el = event.target as HTMLInputElement;
 
-    if (!el.files || !el.files.length) {
+    if (!el.files || !el.files.length || !el.files[0]) {
         return;
     }
 
-    importFile.value = el.files[0];
+    importFile.value = el.files[0] as File;
     el.value = '';
 }
 
diff --git a/src/views/desktop/transactions/import/dialogs/BatchCreateDialog.vue b/src/views/desktop/transactions/import/dialogs/BatchCreateDialog.vue
index 7ca3624e..b8da0ba6 100644
--- a/src/views/desktop/transactions/import/dialogs/BatchCreateDialog.vue
+++ b/src/views/desktop/transactions/import/dialogs/BatchCreateDialog.vue
@@ -75,7 +75,7 @@ import { useI18n } from '@/locales/helpers.ts';
 import { useTransactionCategoriesStore } from '@/stores/transactionCategory.ts';
 import { useTransactionTagsStore } from '@/stores/transactionTag.ts';
 
-import type { NameValue } from '@/core/base.ts';
+import { type NameValue, values } from '@/core/base.ts';
 import { CategoryType } from '@/core/category.ts';
 import { AUTOMATICALLY_CREATED_CATEGORY_ICON_ID } from '@/consts/icon.ts';
 import { DEFAULT_CATEGORY_COLOR } from '@/consts/color.ts';
@@ -140,9 +140,7 @@ function buildBatchCreateCategoryResponse(createdCategories: Record<number, Tran
         displayNameSourceItemMap[item.name] = item.value;
     }
 
-    for (const categoryType in createdCategories) {
-        const categories = createdCategories[categoryType];
-
+    for (const categories of values(createdCategories)) {
         for (const category of categories) {
             if (!category.subCategories || category.subCategories.length < 1) {
                 continue;
diff --git a/src/views/desktop/transactions/list/dialogs/EditDialog.vue b/src/views/desktop/transactions/list/dialogs/EditDialog.vue
index 6f14273a..e2d4c79c 100644
--- a/src/views/desktop/transactions/list/dialogs/EditDialog.vue
+++ b/src/views/desktop/transactions/list/dialogs/EditDialog.vue
@@ -1168,11 +1168,11 @@ function uploadPicture(event: Event): void {
 
     const el = event.target as HTMLInputElement;
 
-    if (!el.files || !el.files.length) {
+    if (!el.files || !el.files.length || !el.files[0]) {
         return;
     }
 
-    const pictureFile = el.files[0];
+    const pictureFile = el.files[0] as File;
 
     el.value = '';
 
diff --git a/src/views/desktop/user/settings/tabs/UserBasicSettingTab.vue b/src/views/desktop/user/settings/tabs/UserBasicSettingTab.vue
index e4d1d789..efb3098e 100644
--- a/src/views/desktop/user/settings/tabs/UserBasicSettingTab.vue
+++ b/src/views/desktop/user/settings/tabs/UserBasicSettingTab.vue
@@ -536,11 +536,11 @@ function updateAvatar(event: Event): void {
 
     const el = event.target as HTMLInputElement;
 
-    if (!el.files || !el.files.length) {
+    if (!el.files || !el.files.length || !el.files[0]) {
         return;
     }
 
-    const avatarFile = el.files[0];
+    const avatarFile = el.files[0] as File;
 
     el.value = '';
 
diff --git a/src/views/mobile/accounts/ListPage.vue b/src/views/mobile/accounts/ListPage.vue
index a97a3f7f..2ac51170 100644
--- a/src/views/mobile/accounts/ListPage.vue
+++ b/src/views/mobile/accounts/ListPage.vue
@@ -87,7 +87,7 @@
                               :after="account.type === AccountType.SingleAccount.type ? accountBalance(account) : ''"
                               :link="!sortable ? '/transaction/list?accountIds=' + account.id : null"
                               :key="account.id"
-                              v-for="account in allCategorizedAccountsMap[accountCategory.type].accounts"
+                              v-for="account in allCategorizedAccountsMap[accountCategory.type]!.accounts"
                               v-show="showHidden || !account.hidden"
                               @taphold="setSortable()"
                 >
diff --git a/src/views/mobile/accounts/ReconciliationStatementPage.vue b/src/views/mobile/accounts/ReconciliationStatementPage.vue
index ef9bcc84..993720f0 100644
--- a/src/views/mobile/accounts/ReconciliationStatementPage.vue
+++ b/src/views/mobile/accounts/ReconciliationStatementPage.vue
@@ -166,7 +166,7 @@
                 <f7-list-item chevron-center
                               :key="item.index"
                               :id="item.transaction ? getTransactionDomId(item.transaction) : undefined"
-                              :class="{ 'transaction-info': item.type == 'transaction', 'last-transaction-of-day': allReconciliationStatementVirtualListItems[item.index + 1] && allReconciliationStatementVirtualListItems[item.index + 1].type === 'date', 'reconciliation-statement-transaction-date': item.type == 'date' }"
+                              :class="{ 'transaction-info': item.type == 'transaction', 'last-transaction-of-day': allReconciliationStatementVirtualListItems[item.index + 1] && allReconciliationStatementVirtualListItems[item.index + 1]!.type === 'date', 'reconciliation-statement-transaction-date': item.type == 'date' }"
                               :style="`top: ${virtualDataItems.topPosition}px`"
                               :virtual-list-index="item.index"
                               :swipeout="item.type === 'transaction' && !!item.transaction"
@@ -204,7 +204,7 @@
                                             {{ tt('Modify Balance') }}
                                         </span>
                                             <span v-else-if="item.transaction.type !== TransactionType.ModifyBalance && allCategoriesMap[item.transaction.categoryId]">
-                                            {{ allCategoriesMap[item.transaction.categoryId].name }}
+                                            {{ allCategoriesMap[item.transaction.categoryId]!.name }}
                                         </span>
                                         </div>
                                     </div>
@@ -466,8 +466,7 @@ const allReconciliationStatementVirtualListItems = computed<ReconciliationStatem
     let index = 0;
     let lastDisplayDate: string | null = null;
 
-    for (let i = 0; i < reconciliationStatements.value.transactions.length; i++) {
-        const transaction = reconciliationStatements.value.transactions[i];
+    for (const transaction of reconciliationStatements.value.transactions) {
         const displayDate = getDisplayDate(transaction);
 
         if (lastDisplayDate !== displayDate) {
diff --git a/src/views/mobile/settings/AccountFilterSettingsPage.vue b/src/views/mobile/settings/AccountFilterSettingsPage.vue
index 0292f6f7..2c34860c 100644
--- a/src/views/mobile/settings/AccountFilterSettingsPage.vue
+++ b/src/views/mobile/settings/AccountFilterSettingsPage.vue
@@ -47,22 +47,22 @@
                       :key="accountCategory.category"
                       v-for="accountCategory in allCategorizedAccounts"
                       v-show="showHidden || accountCategory.allVisibleAccountCount > 0">
-                <f7-accordion-item :opened="collapseStates[accountCategory.category].opened"
-                                   @accordion:open="collapseStates[accountCategory.category].opened = true"
-                                   @accordion:close="collapseStates[accountCategory.category].opened = false">
+                <f7-accordion-item :opened="collapseStates[accountCategory.category]!.opened"
+                                   @accordion:open="collapseStates[accountCategory.category]!.opened = true"
+                                   @accordion:close="collapseStates[accountCategory.category]!.opened = false">
                     <f7-block-title>
                         <f7-accordion-toggle>
                             <f7-list strong inset dividers
                                      class="combination-list-header"
-                                     :class="collapseStates[accountCategory.category].opened ? 'combination-list-opened' : 'combination-list-closed'">
+                                     :class="collapseStates[accountCategory.category]!.opened ? 'combination-list-opened' : 'combination-list-closed'">
                                 <f7-list-item group-title>
                                     <small>{{ tt(accountCategory.name) }}</small>
-                                    <f7-icon class="combination-list-chevron-icon" :f7="collapseStates[accountCategory.category].opened ? 'chevron_up' : 'chevron_down'"></f7-icon>
+                                    <f7-icon class="combination-list-chevron-icon" :f7="collapseStates[accountCategory.category]!.opened ? 'chevron_up' : 'chevron_down'"></f7-icon>
                                 </f7-list-item>
                             </f7-list>
                         </f7-accordion-toggle>
                     </f7-block-title>
-                    <f7-accordion-content :style="{ height: collapseStates[accountCategory.category].opened ? 'auto' : '' }">
+                    <f7-accordion-content :style="{ height: collapseStates[accountCategory.category]!.opened ? 'auto' : '' }">
                         <f7-list strong inset dividers accordion-list class="combination-list-content">
                             <f7-list-item checkbox
                                           :class="{ 'has-child-list-item': account.type === AccountType.MultiSubAccounts.type && ((showHidden && accountCategory.allSubAccounts[account.id]) || accountCategory.allVisibleSubAccountCounts[account.id]) }"
@@ -189,9 +189,7 @@ function getCollapseStates(): Record<number, CollapseState> {
     const collapseStates: Record<number, CollapseState> = {};
     const allCategories = AccountCategory.values();
 
-    for (let i = 0; i < allCategories.length; i++) {
-        const accountCategory = allCategories[i];
-
+    for (const accountCategory of allCategories) {
         collapseStates[accountCategory.type] = {
             opened: true
         };
diff --git a/src/views/mobile/settings/CategoryFilterSettingsPage.vue b/src/views/mobile/settings/CategoryFilterSettingsPage.vue
index b418eb4b..5beb52c2 100644
--- a/src/views/mobile/settings/CategoryFilterSettingsPage.vue
+++ b/src/views/mobile/settings/CategoryFilterSettingsPage.vue
@@ -52,22 +52,22 @@
                   :key="categoryType.type"
                   v-for="categoryType in allTransactionCategories"
                   v-else-if="!loading">
-            <f7-accordion-item :opened="collapseStates[categoryType.type].opened"
-                               @accordion:open="collapseStates[categoryType.type].opened = true"
-                               @accordion:close="collapseStates[categoryType.type].opened = false">
+            <f7-accordion-item :opened="collapseStates[categoryType.type]!.opened"
+                               @accordion:open="collapseStates[categoryType.type]!.opened = true"
+                               @accordion:close="collapseStates[categoryType.type]!.opened = false">
                 <f7-block-title>
                     <f7-accordion-toggle>
                         <f7-list strong inset dividers
                                  class="combination-list-header"
-                                 :class="collapseStates[categoryType.type].opened ? 'combination-list-opened' : 'combination-list-closed'">
+                                 :class="collapseStates[categoryType.type]!.opened ? 'combination-list-opened' : 'combination-list-closed'">
                             <f7-list-item group-title>
                                 <small>{{ getCategoryTypeName(categoryType.type) }}</small>
-                                <f7-icon class="combination-list-chevron-icon" :f7="collapseStates[categoryType.type].opened ? 'chevron_up' : 'chevron_down'"></f7-icon>
+                                <f7-icon class="combination-list-chevron-icon" :f7="collapseStates[categoryType.type]!.opened ? 'chevron_up' : 'chevron_down'"></f7-icon>
                             </f7-list-item>
                         </f7-list>
                     </f7-accordion-toggle>
                 </f7-block-title>
-                <f7-accordion-content :style="{ height: collapseStates[categoryType.type].opened ? 'auto' : '' }">
+                <f7-accordion-content :style="{ height: collapseStates[categoryType.type]!.opened ? 'auto' : '' }">
                     <f7-list strong inset dividers accordion-list class="combination-list-content" v-if="!hasAvailableCategory[categoryType.type]">
                         <f7-list-item :title="tt('No available category')"></f7-list-item>
                     </f7-list>
@@ -242,7 +242,7 @@ function updateAllSubCategoriesSelected(e: Event): void {
     const categoryId = target.value;
     const category = transactionCategoriesStore.allTransactionCategoriesMap[categoryId];
 
-    selectAllSubCategories(filterCategoryIds.value, category, !target.checked);
+    selectAllSubCategories(filterCategoryIds.value, !target.checked, category);
 }
 
 function selectAllCategories(): void {
diff --git a/src/views/mobile/settings/TransactionTagFilterSettingsPage.vue b/src/views/mobile/settings/TransactionTagFilterSettingsPage.vue
index 5f244cfc..0a2d61b2 100644
--- a/src/views/mobile/settings/TransactionTagFilterSettingsPage.vue
+++ b/src/views/mobile/settings/TransactionTagFilterSettingsPage.vue
@@ -51,22 +51,22 @@
                 </f7-list-item>
             </f7-list>
 
-            <f7-accordion-item :opened="collapseStates['default'].opened"
-                               @accordion:open="collapseStates['default'].opened = true"
-                               @accordion:close="collapseStates['default'].opened = false">
+            <f7-accordion-item :opened="collapseStates['default']!.opened"
+                               @accordion:open="collapseStates['default']!.opened = true"
+                               @accordion:close="collapseStates['default']!.opened = false">
                 <f7-block-title>
                     <f7-accordion-toggle>
                         <f7-list strong inset dividers
                                  class="combination-list-header"
-                                 :class="collapseStates['default'].opened ? 'combination-list-opened' : 'combination-list-closed'">
+                                 :class="collapseStates['default']!.opened ? 'combination-list-opened' : 'combination-list-closed'">
                             <f7-list-item group-title>
                                 <small>{{ tt('Tags') }}</small>
-                                <f7-icon class="combination-list-chevron-icon" :f7="collapseStates['default'].opened ? 'chevron_up' : 'chevron_down'"></f7-icon>
+                                <f7-icon class="combination-list-chevron-icon" :f7="collapseStates['default']!.opened ? 'chevron_up' : 'chevron_down'"></f7-icon>
                             </f7-list-item>
                         </f7-list>
                     </f7-accordion-toggle>
                 </f7-block-title>
-                <f7-accordion-content :style="{ height: collapseStates['default'].opened ? 'auto' : '' }">
+                <f7-accordion-content :style="{ height: collapseStates['default']!.opened ? 'auto' : '' }">
                     <f7-list strong inset dividers accordion-list class="combination-list-content">
                         <f7-list-item checkbox
                                       :title="transactionTag.name"
diff --git a/src/views/mobile/transactions/AmountFilterPage.vue b/src/views/mobile/transactions/AmountFilterPage.vue
index d4feccb3..d13704a6 100644
--- a/src/views/mobile/transactions/AmountFilterPage.vue
+++ b/src/views/mobile/transactions/AmountFilterPage.vue
@@ -119,13 +119,13 @@ function init(): void {
     if (isString(query['value'])) {
         try {
             const filterItems = query['value'].split(':');
-            const amountCount = getAmountFilterParameterCount(filterItems[0]);
+            const amountCount = getAmountFilterParameterCount(filterItems[0] as string);
 
             if (filterItems.length === 2 && amountCount === 1) {
-                queryAmount1 = parseInt(filterItems[1]);
+                queryAmount1 = parseInt(filterItems[1] as string);
             } else if (filterItems.length === 3 && amountCount === 2) {
-                queryAmount1 = parseInt(filterItems[1]);
-                queryAmount2 = parseInt(filterItems[2]);
+                queryAmount1 = parseInt(filterItems[1] as string);
+                queryAmount2 = parseInt(filterItems[2] as string);
             }
         } catch (ex) {
             logger.warn('cannot parse amount from filter value, original value is ' + query['value'], ex);
diff --git a/src/views/mobile/transactions/EditPage.vue b/src/views/mobile/transactions/EditPage.vue
index af3ca48f..87379466 100644
--- a/src/views/mobile/transactions/EditPage.vue
+++ b/src/views/mobile/transactions/EditPage.vue
@@ -721,9 +721,9 @@ const transactionDisplayScheduledFrequency = computed<string>(() => {
     const items = (template.scheduledFrequency || '').split(',');
     const scheduledFrequencyValues: number[] = [];
 
-    for (let i = 0; i < items.length; i++) {
-        if (items[i]) {
-            scheduledFrequencyValues.push(parseInt(items[i]));
+    for (const item of items) {
+        if (item) {
+            scheduledFrequencyValues.push(parseInt(item));
         }
     }
 
@@ -912,7 +912,7 @@ function init(): void {
             if (query['id'] && responses[4] instanceof Transaction) {
                 fromTransaction = responses[4];
             } else if (query['templateId'] && transactionTemplatesStore.allTransactionTemplatesMap && transactionTemplatesStore.allTransactionTemplatesMap[TemplateType.Normal.type]) {
-                fromTransaction = transactionTemplatesStore.allTransactionTemplatesMap[TemplateType.Normal.type][query['templateId']];
+                fromTransaction = (transactionTemplatesStore.allTransactionTemplatesMap[TemplateType.Normal.type] as Record<string, TransactionTemplate>)[query['templateId']] ?? null;
 
                 if (fromTransaction) {
                     addByTemplateId.value = fromTransaction.id;
@@ -1163,7 +1163,7 @@ function uploadPicture(event: Event): void {
         return;
     }
 
-    const pictureFile = el.files[0];
+    const pictureFile = el.files[0] as File;
 
     el.value = '';
 
diff --git a/src/views/mobile/users/SessionListPage.vue b/src/views/mobile/users/SessionListPage.vue
index 1b2143bf..581b7f30 100644
--- a/src/views/mobile/users/SessionListPage.vue
+++ b/src/views/mobile/users/SessionListPage.vue
@@ -53,6 +53,7 @@ import { useI18nUIComponents, showLoading, hideLoading, onSwipeoutDeleted } from
 
 import { useTokensStore } from '@/stores/token.ts';
 
+import { itemAndIndex, reversedItemAndIndex } from '@/core/base.ts';
 import { TextDirection } from '@/core/text.ts';
 import { type TokenInfoResponse, SessionInfo } from '@/models/token.ts';
 
@@ -94,8 +95,7 @@ const sessions = computed<MobilePageSessionInfo[]>(() => {
         return sessions;
     }
 
-    for (let i = 0; i < tokens.value.length; i++) {
-        const token = tokens.value[i];
+    for (const token of tokens.value) {
         const sessionInfo = parseSessionInfo(token);
         sessions.push(new MobilePageSessionInfo(sessionInfo));
     }
@@ -171,9 +171,9 @@ function revoke(session: SessionInfo): void {
             hideLoading();
 
             onSwipeoutDeleted(getTokenDomId(session.tokenId), () => {
-                for (let i = 0; i < tokens.value.length; i++) {
-                    if (tokens.value[i].tokenId === session.tokenId) {
-                        tokens.value.splice(i, 1);
+                for (const [ token, index ] of itemAndIndex(tokens.value)) {
+                    if (token.tokenId === session.tokenId) {
+                        tokens.value.splice(index, 1);
                     }
                 }
             });
@@ -198,9 +198,9 @@ function revokeAll(): void {
         tokensStore.revokeAllTokens().then(() => {
             hideLoading();
 
-            for (let i = tokens.value.length - 1; i >= 0; i--) {
-                if (!tokens.value[i].isCurrent) {
-                    tokens.value.splice(i, 1);
+            for (const [ token, index ] of reversedItemAndIndex(tokens.value)) {
+                if (!token.isCurrent) {
+                    tokens.value.splice(index, 1);
                 }
             }
 
diff --git a/src/views/mobile/users/UserProfilePage.vue b/src/views/mobile/users/UserProfilePage.vue
index cb200180..72101caf 100644
--- a/src/views/mobile/users/UserProfilePage.vue
+++ b/src/views/mobile/users/UserProfilePage.vue
@@ -666,9 +666,9 @@ const allLanguages = computed<LanguageOption[]>(() => getAllLanguageOptions(true
 const allCurrencies = computed<LocalizedCurrencyInfo[]>(() => getAllCurrencies());
 
 const currentLanguageName = computed<string>(() => {
-    for (let i = 0; i < allLanguages.value.length; i++) {
-        if (allLanguages.value[i].languageTag === newProfile.value.language) {
-            return allLanguages.value[i].nativeDisplayName;
+    for (const lang of allLanguages.value) {
+        if (lang.languageTag === newProfile.value.language) {
+            return lang.nativeDisplayName;
         }
     }