javascript js 操作数组 增删改查的简单实现

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);
  }
};
Array.prototype.insert = function (index, item) {
 this.splice(index, 0, item);

};