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());//3
    console.log(n);//4

/*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();//4

/*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));//7

/**/
    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