jQuery.stringify() utility

jQuery.stringify.js

/**
 * converted stringify() to jQuery plugin.
 * serializes a simple object to a JSON formatted string.
 * Note: stringify() is different from jQuery.serialize() which URLEncodes form elements

 * UPDATES:
 *      Added a fix to skip over Object.prototype members added by the prototype.js library
 * USAGE:
 *  jQuery.ajax({
 *	    data : {serialized_object : jQuery.stringify (JSON_Object)},
 *		success : function (data) {
 *
 *		}
 *   });
 *
 * CREDITS: http://blogs.sitepointstatic.com/examples/tech/json-serialization/json-serialization.js
 */
jQuery.extend({
    stringify  : function stringify(obj) {
        var t = typeof (obj);
        if (t != "object" || obj === null) {
            // simple data type
            if (t == "string") obj = '"' + obj + '"';
            return String(obj);
        } else {
            // recurse array or object
            var n, v, json = [], arr = (obj && obj.constructor == Array);

            for (n in obj) {
                v = obj[n];
                t = typeof(v);
                if (obj.hasOwnProperty(n)) {
                    if (t == "string") v = '"' + v + '"'; else if (t == "object" && v !== null) v = jQuery.stringify(v);
                    json.push((arr ? "" : '"' + n + '":') + String(v));
                }
            }
            return (arr ? "[" : "{") + String(json) + (arr ? "]" : "}");
        }
    }
});

Hey, thanks for that! Is this plugin free to use or does it have a licence model (MIT or similar)?