Php uniqid() function in Javascript

function uniqid (prefix, more_entropy) {
    // +   original by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // +    revised by: Kankrelune (http://www.webfaktory.info/)
    // %        note 1: Uses an internal counter (in php_js global) to avoid collision
    // *     example 1: uniqid();
    // *     returns 1: 'a30285b160c14'
    // *     example 2: uniqid('foo');
    // *     returns 2: 'fooa30285b1cd361'
    // *     example 3: uniqid('bar', true);
    // *     returns 3: 'bara20285b23dfd1.31879087'
    if (typeof prefix == 'undefined') {
        prefix = "";
    }

    var retId;
    var formatSeed = function (seed, reqWidth) {
        seed = parseInt(seed, 10).toString(16); // to hex str
        if (reqWidth < seed.length) { // so long we split
            return seed.slice(seed.length - reqWidth);
        }
        if (reqWidth > seed.length) { // so short we pad
            return Array(1 + (reqWidth - seed.length)).join('0') + seed;
        }
        return seed;
    };

    // BEGIN REDUNDANT
    if (!this.php_js) {
        this.php_js = {};
    }
    // END REDUNDANT
    if (!this.php_js.uniqidSeed) { // init seed with big random int
        this.php_js.uniqidSeed = Math.floor(Math.random() * 0x75bcd15);
    }
    this.php_js.uniqidSeed++;

    retId = prefix; // start with prefix, add current milliseconds hex string
    retId += formatSeed(parseInt(new Date().getTime() / 1000, 10), 8);
    retId += formatSeed(this.php_js.uniqidSeed, 5); // add seed hex string
    if (more_entropy) {
        // for more entropy we add a float lower to 10
        retId += (Math.random() * 10).toFixed(8).toString();
    }

    return retId;
}