if IndexOf isn't defined on IE

gistfile1.js

indexOf4Array = function () {
    if (!Array.indexOf) {
        Array.prototype.indexOf = function(obj) {
            var length = this.length;
            for (var i = 0; i < length; i++) {
                if (this[i] === obj) {
                    return i;
                }
            }
            return -1;
        };
    }
};