js 数组 删除数组中指定下标返回新数组

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
}
var a = [1, 2, 3, 4, 5];    //目标数组
a.remove(4);           //删除目标数组的下标
console.log(a)