Storage helper with record versioning and expiration support

storageHelper

// initialization: initializeStorage(localStorage);
// usage: storageSetItem("key", "value");
//        storageGetItem("key");
//        storageRemoveItem("key");

const StorageKeyPrefix = "YourPrefix";
const StorageKeyVersionedPrefix = `${StorageKeyPrefix}_v1_`;
const DefaultStorageItemExpirationInMiliseconds = 14 * 24 * 60 * 60 * 1000; // 14 days

export class StorageItem {
    timestamp: number;
    value: string;

    constructor(timestamp: number, value: string) {
        this.timestamp = timestamp;
        this.value = value;
    }
}

export interface IStorage  {
    getItem(key): string | null;
    setItem(key: string, value: string);
    removeItem(key: string);
};

let _storage: IStorage;
let _storageItemExpirationInMiliseconds: number;
let _storageKeyVersionedPrefix: string = StorageKeyVersionedPrefix;

export function getStoragePrefixedKey(key: string): string {
    return `${_storageKeyVersionedPrefix}${key}`;
}

export function initializeStorage(
    storage: IStorage,
    storageItemExpirationInMiliseconds: number = DefaultStorageItemExpirationInMiliseconds
) {
    _storage = storage;
    _storageItemExpirationInMiliseconds = storageItemExpirationInMiliseconds;
    storagePurgeExpiredItems();
}

function getStorage(): IStorage {
    if (!_storage) throw new Error("Storage is not initialized. Call initializeStorage() first.");
    return _storage;
}

export function storageSetItem(key: string, value: string) {
    getStorage().setItem(
        getStoragePrefixedKey(key),
        JSON.stringify(new StorageItem(Date.now(), value))
    );
}

export function storageGetItem(key: string): string | null {
    const valueWithExpiration = getStorage().getItem(getStoragePrefixedKey(key));
    if (!valueWithExpiration) return null;

    const storageItem = JSON.parse(valueWithExpiration) as StorageItem;
    return storageItem.value;
}

export function storageRemoveItem(key: string) {
    getStorage().removeItem(getStoragePrefixedKey(key));
}

export function storagePurgeExpiredItems() {
    const storage = getStorage();
    const storageItemKeys = Object.keys(storage);
    storageItemKeys.forEach(key => {
        if (!key.startsWith(StorageKeyPrefix)) return;

        if (!key.startsWith(StorageKeyVersionedPrefix)) {
            storage.removeItem(key);
            return;
        }

        const storageItem = JSON.parse(storage.getItem(key)!) as StorageItem;
        const expirationDateTime = storageItem.timestamp + _storageItemExpirationInMiliseconds;
        if (expirationDateTime < Date.now()) {
            storage.removeItem(key);
        }
    });
}

export function setStorageVersionedPrefix(storageKeyVersionedPrefix: string) {
    _storageKeyVersionedPrefix = storageKeyVersionedPrefix;
}