javascript array method "indexOf" doesn't exists in IE, so this code implements this.

indexOf IE

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