js怎么删数组固定的值

 <script type="text/javascript">
        Array.prototype.indexOf = function(val) {
            for (var i = 0; i < this.length; i++) {
                if (this[i] == val) return i;
            }
            return -1;
        };
        Array.prototype.remove = function(val) {
            var index = this.indexOf(val);
            if (index > -1) {
                this.splice(index, 1);
            }
        };

        var array = [1, 2, 3, 4, 5];
        array.remove(3);

    </script>