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66 lines
2.2 KiB
66 lines
2.2 KiB
/**
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* Expose localStorage and sessionStorage with fallbacks for cases when they don't work (e.g.
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* cross-domain embeds in Firefox and Safari).
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*
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* Usage:
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* import {getStorage, getSessionStorage} from 'app/client/lib/storage';
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* ... use getStorage() in place of localStorage...
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* ... use getSessionStorage() in place of sessionStorage...
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*/
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/**
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* Returns localStorage if functional, or sessionStorage, or an in-memory storage. The fallbacks
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* help with tests, and when Grist is embedded.
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*/
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export function getStorage(): Storage {
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_storage ??= testStorage('localStorage') || getSessionStorage();
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return _storage;
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}
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/**
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* Return window.sessionStorage, or when not available, an in-memory storage.
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*/
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export function getSessionStorage(): Storage {
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// If can't use sessionStorage, fall back to a Map-based non-persistent implementation.
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_sessionStorage ??= testStorage('sessionStorage') || createInMemoryStorage();
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return _sessionStorage;
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}
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let _storage: Storage|undefined;
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let _sessionStorage: Storage|undefined;
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/**
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* Returns the result of window[storageName] if storage is functional, or null otherwise. In some
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* cases (e.g. when embedded), using localStorage may throw errors, in which case we return null.
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* This is similar to the approach taken by store.js.
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*/
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function testStorage(storageName: 'localStorage'|'sessionStorage'): Storage|null {
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try {
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const testStr = '__localStorage_test';
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const storage = window[storageName];
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storage.setItem(testStr, testStr);
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const ok = (storage.getItem(testStr) === testStr);
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storage.removeItem(testStr);
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if (ok) {
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return storage;
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}
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} catch (e) {
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// Fall through
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}
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console.warn(`${storageName} is not available; will use fallback`);
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return null;
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}
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function createInMemoryStorage(): Storage {
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const values = new Map<string, string>();
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return {
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setItem(key: string, val: string) { values.set(key, val); },
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getItem(key: string) { return values.get(key) ?? null; },
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removeItem(key: string) { values.delete(key); },
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clear() { values.clear(); },
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get length() { return values.size; },
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key(index: number): string|null { throw new Error('Not implemented'); },
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};
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}
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