Redis style API wrapper around localforage as a cache mechanism

CacheClient.js

import storage from 'localforage';

/**
 * Redis style API wrapper around localforage as a cache mechanism
 */
export default class CacheClient {
    constructor(config) {
        defaultConfig = {
            cacheDuration: 600, // 1o mins
        };
        
        this.config = Object.assign({}, defaultConfig, config);

        // By default mock out the storage interface
        // TODO set up an inmemory store as a fallback
        this.db = {
            getItem: () => Promise.resolve(null),
            setItem: () => Promise.resolve(null),
            removeItem: () => Promise.resolve(null),
        };

        storage.ready().then(() => {
            this.db = storage;
        }).catch((e) => {
            console.error('[Cache Client] error could not set up database', e); // `No available storage method found.`
        });
    }

    /**
     * Return an item from cache
     * @param key
     * @returns {Request|Promise.<TResult>|*}
     */
    get(key) {
        return this.db.getItem(key)
            .then((record) => {
                if (record) {
                    if (!record.ts || (new Date()).getTime() < parseInt(record.ts, 10)) {
                        // If there is no expiry timestamp, or if the expiry time hasn't been reached yet
                        return record.value;
                    }

                    // If time has passed, remove the record from the cache
                    return this.db.removeItem(key);
                }

                return record;
            });
    }

    /**
     * Adds an item to cache
     * @param key
     * @param value
     * @param ttl
     * @returns {*}
     */
    set(key, value, ttl) {
        const cacheTTL = ttl || this.config.cacheDuration;

        const record = {
            value,
            // Multiply ttl by 1000 to convert it to milliseconds
            ts: (new Date()).getTime() + parseInt(cacheTTL * 1000, 10),
        };

        return this.db.setItem(key, record);
    }

    /**
     * Removes an item from cache
     * @param key
     * @returns {*}
     */
    remove(key) {
        // If time has passed, remove the record from the cache
        return this.db.removeItem(key);
    }
}