1 Array.prototype.indexOf = function (val) {
2     for (var i = 0; i < this.length; i++) {
3         if (this[i] == val) return i;
4     }
5     return -1;
6 };

1 Array.prototype.remove = function (val) {
2     var index = this.indexOf(val);
3     if (index > -1) {
4         this.splice(index, 1);
5     }
6 };

1 Array.prototype.pushDistinct = function (val) {
2     var index = this.indexOf(val);
3     if (index == -1) {
4         this.push(val);
5     }
6 };