如何使用 Javascript 实现 ArrayList

 function ArrayList(){
  	this.arr=[],
  	this.size=function(){
  		return this.arr.length;
  	},
  	this.add=function(){
  		if(arguments.length==1){
  			this.arr.push(arguments[0]);
  		}else if(arguments.length>=2){
  			var deleteItem=this.arr[arguments[0]];
  			this.arr.splice(arguments[0],1,arguments[1],deleteItem)
  		}
  		return this;
  	},
  	this.get=function(index){
  		return this.arr[index];
  	},
  	this.removeIndex=function(index){
  		this.arr.splice(index,1);
  	},
  	this.removeObj=function(obj){
  		this.removeIndex(this.indexOf(obj));
  	},
  	this.indexOf=function(obj){
  		for(var i=0;i<this.arr.length;i++){
  			if (this.arr[i]===obj) {
  				return i;
  			};
  		}
  		return -1;
  	},
  	this.isEmpty=function(){
  		return this.arr.length==0;
  	},
  	this.clear=function(){
  		this.arr=[];
  	},
  	this.contains=function(obj){
  		return this.indexOf(obj)!=-1;
  	}
 
  };