parse-query-string.js

var parseQueryString = (function (overlap) {
	return function (qs) {
		var kv = qs.split('&');
		var obj = {};
		for (var i = 0, l = kv.length; i < l; i ++) {
			kv[i] = kv[i].split('=');
			var key = decodeURIComponent(kv[i].shift());
			var val = decodeURIComponent(kv[i].join('='));
			var keyparts = key.match(/^([^\[]+)(.*)$/);
			if (!keyparts) continue;
			keyparts.shift();
			if (keyparts.length === 1) {
				// easy. simple key/value pair
				obj[keyparts[0]] = val;
			} else {
				// more complex.
				// array or object.
				// create the "tmpobj", and then merge it in.
				var subkeys = keyparts[1].replace(/^\[/, '').replace(/\]$/, '').split('][');
				var tmpobj, tmpkey;
				while (undefined !== (tmpkey = subkeys.pop())) {
					if (tmpkey === '') {
						// array
						tmpobj = [val];
					} else {
						tmpobj = {};
						tmpobj[tmpkey] = val;
					}
					val = tmpobj;
				}
				if (!obj.hasOwnProperty(keyparts[0])) {
					obj[keyparts[0]] = val;
				} else {
					tmpobj = {};
					tmpobj[keyparts[0]] = val;
					obj = overlap(obj, tmpobj);
				}
			}
		}
		return obj;
	};
})(function (into, from) {
	if (Y.Lang.isObject(into) && Y.Lang.isObject(from)) {
		for (var i in from) if (from.hasOwnProperty(i) && i.slice(-3) !== '___') {
			into[i] = arguments.callee(into[i], from[i]);
		}
		return into;
	} else if (Y.Lang.isArray(into) && Y.Lang.isArray(from)) {
		return into.concat(from);
	} else {
		// type mismatch, just overwrite.
		return from;
	}
});