JAVASCRIPT中经典面试题

 //1、try catch finally中的return
     var n=1;
     function fun(){
         try{
             n++;
             m++;//报错
             return n;
         }catch(err){
             n++;
             return n;
         }finally{
             n++;
             //return n;
         }
     }
     console.log(fun());//
     console.log(n);//

/*作用域和作用域链*/
	var n=10;
	function fun(n){
		n--;
		console.log(n);
	}
	console.log(fun(n)); //9
	console.log(n); //10

 /*new Function*/
     var i=5;
     function fun(){
         var i=4;
         //var f1=new Function("console.log(i)");
         var f1=function(){console.log(i);};
         console.log(f1);
         f1();
     }
     fun();//

 /*callback 与 this*/
     var o={
         n:1,
         fun:function(){
             var self=this;//留住this
             console.log(self.n++);
             setTimeout(function(){
                 self.fun();
             },1000);
         }
     }
     o.fun();//this-->o

 /*DOM中的闭包问题*/
     function fun(){
         var li=document.getXX...;
         btn.onclick=function(){
             li.xx=xx;
         }//li将永远无法释放，即使刷新页面也不行
     }

 /*引用类型的共有属性*/
     function Student(){}
     Student.prototype.arr=[];
     var lilei=new Student();
     var hmm=new Student();
     lilei.arr.push(1);//this[this.length]=1
     hmm.arr[1]=2;
     console.log(lilei.arr);//[1,2]
     console.log(hmm.arr);//[1,2]

 /*继承父类型共有方法*/
     function Student(){}
     Student.prototype=[];
     var lilei=new Student();
     lilei.push(1);//this[this.length]=value;
     var hmm=new Student();
     hmm.push(2);
     console.log(lilei);
     console.log(hmm);

 /*私有属性，公有属性*/
     function Student(){
         var prop="私有属性";//私有属性
         this.prop="公有属性"; //公有属性
         var fun=function(){//私有方法
             console.log("调用私有方法");
             console.log(prop);
         }
         this.fun=function(){//公有方法
             console.log("调用公有方法");
             fun();//this-->window
             console.log(prop);
             console.log(this.prop);
         }
     }
     var lilei=new Student();
     lilei.fun();//公有

 //阻碍事件
 for(var i=0;i<3;i++){
         setTimeout(function(){
             console.log(i);
         },10)
     }
     alert("hello");

 function MyObj(){
         this.p.pid++;
     }
     MyObj.prototype.p={"pid":0};
     MyObj.prototype.getNum=function(num){
         return this.p.pid+num;
     }
     var obj1=new MyObj();
     var obj2=new MyObj(); //p.pid=2
     console.log(obj1.getNum(1)+obj2.getNum(2));//

 /**/
     function fun(n,o){
         console.log(o);
         return {fun:function(m){
                 return fun(m,n);
             }
         }
     }
     var a=fun(0);//undefined
     //a-->{fun:function(m){return fun(m,n)}}
     a.fun(1); a.fun(2); a.fun(3); //0 0 0
     var b=fun(0).fun(1).fun(2).fun(3); //0 1 2
     var c=fun(0).fun(1); c.fun(2);c.fun(3); //0 1 1