Function Disqus uses for hashing session id to integer http://stackoverflow.com/questions/7616461/generate-a-hash-from-string-in-javascript-jquery

hash.js

/**
 * The string hash function from Java.
 *
 * Borrowed from http://stackoverflow.com/questions/7616461/generate-a-hash-from-string-in-javascript-jquery
 * @param  {String} str
 * @return {Number}
 */
function hash(str) {
    var hash = 0, i, l, charCode;
    if (str.length === 0)
        return hash;
    for (i = 0, l = str.length; i < l; i++) {
        charCode = str.charCodeAt(i);

        /* jshint bitwise: false */
        hash = ((hash << 5) - hash) + charCode;
        // Convert to 32bit integer
        hash |= 0;
    }
    return hash;
};