JavaScript: Java String.hashCode() implementation. Source: http://goo.gl/Hyt1ku

hashcode.js

String.prototype.hashCode = function() {
    var hash = 0;

    try {
    
        if (this.length == 0) return hash;

        for (i = 0; i < this.length; i++) {
            char = this.charCodeAt(i);
            hash = ((hash << 5) - hash) + char;
            hash = hash & hash; // Convert to 32bit integer
        }
        return hash;
        
    } catch (e) {
        throw new Error('hashCode: ' + e);
    }
};