JS 数组的删除与判断是否存在的两个扩展方法

       Array.prototype.remove = function (dx) {
            if (isNaN(dx) || dx > this.length) {
                return false;
            }
            for (var i = 0, n = 0; i < this.length; i++) {
                if (this[i] != this[dx]) {
                    this[n++] = this[i];
                }
            }
            this.length -= 1;
            return false;
        };

        Array.prototype.contains = function (item) {
            return RegExp("\\b" + item + "\\b").test(this);
        };