47 lines
1.2 KiB
JavaScript
47 lines
1.2 KiB
JavaScript
import { Store } from 'svelte/store'
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const LS = process.browser && localStorage
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function safeParse (str) {
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return !str ? undefined : (str === 'undefined' ? undefined : JSON.parse(str))
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}
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export class LocalStorageStore extends Store {
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constructor (state, keysToWatch) {
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super(state)
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if (!process.browser) {
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return
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}
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this._keysToWatch = keysToWatch
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this._keysToSave = {}
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let newState = {}
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for (let i = 0, len = LS.length; i < len; i++) {
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let key = LS.key(i)
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if (key.startsWith('store_')) {
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let item = LS.getItem(key)
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newState[key.substring(6)] = safeParse(item)
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}
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}
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this.set(newState)
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this.onchange((state, changed) => {
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Object.keys(changed).forEach(change => {
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if (this._keysToWatch.has(change)) {
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this._keysToSave[change] = true
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}
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})
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})
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if (process.browser) {
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window.addEventListener('beforeunload', () => this.save())
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}
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}
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save () {
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if (!process.browser) {
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return
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}
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Object.keys(this._keysToSave).forEach(key => {
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LS.setItem(`store_${key}`, JSON.stringify(this.get(key)))
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})
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this._keysToSave = {}
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}
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}
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