Discussion on: Memoization in JavaScript

[Clay Ferguson]

I recently had a need to cache the results of decryption of an encrypted string so that decryption only runs once, and ended up using a cache where the 'key' of the cache is the hash of the string. Here's the hashing functions I have:

    hashOfString = (s: string): string => {
        let hash = 0;
        let i = 0;
        let chr = 0;
        if (s.length === 0) return hash.toString();

        for (i = 0; i < s.length; i++) {
            chr = s.charCodeAt(i);
            hash = ((hash << 5) - hash) + chr;
            hash |= 0; // Convert to 32bit integer
        }
        return hash.toString();
    }

    hashOfObject = (obj: Object): string => {
        if (!obj) return "null";
        return this.hashOfString(JSON.stringify(obj));
    }

Although the above isn't perfectly good in terms of avoiding hash collisions. I guess I should boost it up to a SHA-256 to be more 'solid' code.