Schema-based persistent key-value meta storage

/**
 * @file Manages metadata and persists it to LocalStorage.
 */

type LocalMetaSchema = {
    muted: boolean
};

type LocalMetaKey = keyof LocalMetaSchema;

class LocalMeta {
    private _key: string;
    private _mem: Record<string, any> = {}

    constructor(storageKey: string, initialState: LocalMetaSchema) {
        this._key = storageKey;

        try {
            // Attempt to load meta from disk.
            const raw = localStorage.getItem(this._key);
            if (raw === null) throw Error();
            this._mem = JSON.parse(raw);
        } catch {
            // Remove (possibly corrupt) saved meta.
            console.log('Failed to load meta from LocalStorage.');
            localStorage.removeItem(this._key);

            // Set from initial state.
            this._mem = initialState;
            this._persist();
        }
    }

    // Persists in-memory meta to disk.
    private _persist() {
        localStorage.setItem(this._key, JSON.stringify(this._mem));
    }

    // Sets a meta value.
    public set<K extends LocalMetaKey, V extends LocalMetaSchema[K]>(key: K, value: V) {
        // Save in memory and on disk.
        this._mem[key] = value;
        this._persist();
    }

    // Gets a meta value.
    public get<K extends LocalMetaKey, V extends LocalMetaSchema[K]>(key: K): V {
        return this._mem[key];
    }
}

// Export singleton.
const metaKey = process.env.LOCAL_STORAGE_KEY || 'meta';
const initialState: LocalMetaSchema = {
    muted: false,
};
export default new LocalMeta(metaKey, initialState);