code refactor

src/lib/settings.js

@@ -0,0 +1,43 @@
+const settingsLocalStorageKey = 'lab_user_settings';
+const defaultSettings = {
+    lang: 'en'
+};
+
+function getOriginalSettings() {
+    try {
+        const storageData = localStorage.getItem(settingsLocalStorageKey) || '{}';
+        return JSON.parse(storageData);
+    } catch (ex) {
+        console.warn('settings in local storage is invalid', ex);
+        return {};
+    }
+}
+
+function getFinalSettings() {
+    return Object.assign({}, defaultSettings, getOriginalSettings());
+}
+
+function setSettings(settings) {
+    const storageData = JSON.stringify(settings);
+    return localStorage.setItem(settingsLocalStorageKey, storageData);
+}
+
+function getOriginalOption(key) {
+    return getOriginalSettings()[key];
+}
+
+function setOption(key, value) {
+    if (!Object.prototype.hasOwnProperty.call(defaultSettings, key)) {
+        return;
+    }
+
+    const settings = getFinalSettings();
+    settings[key] = value;
+
+    return setSettings(settings);
+}
+
+export default {
+    getLanguage: () => getOriginalOption('lang'),
+    setLanguage: value => setOption('lang', value)
+};