js中Array自定义contains, indexOf, delete方法.

Array.prototype.contains = function (elem) {
 for (var i = 0; i < this.length; i++) {
      if (this[i] == elem) {
       return true;
     }
   }
  return false;
 }

Array.prototype.indexOf = function(o){   

    for(var i = 0 ;  i<this.length;i++){

           if(this[i] == o){

                            return i;

           }           return -1;     } };

Array.prototype.delete = function(o){

   var index = this.indexOf(o);

           if(index != -1){

                 this.splice(index,1)

             }

           return this;

}