js面试题

  知识点

1.js面向对象
function Func(name,age){
    this.Name = name;
    this.Age = age
}
obj = new Func('alex',18)

2.this关键字
#每个函数都有this
#函数调用时，this=window
#类new时，this=obj

function func(name,age){
    #当做函数执行时，this=window
    console.log(this);
}

func()

function Func(name,age){
    #当做函数执行时，this=window
    console.log(this);
}

obj = new Func()

3.js中无字典，只有对象
Name='alex';
obj = {
    Name:'root',
    Age:18,
    Func:function(){
        #this=obj
        console.log(this.Name) #root
        var that=this
        function inner(){
            #this=window
            #that=obj
            console.log(this.Name)  #alex
            console.log(that.Name)  #root
        }
        inner()
        //自执行函数
        (function(){
            console.log(this.Name)
        }()
    },
}
相当于new了对象obj

　面试题

js面试题：
题目1. 代码在执行之前，作用域已经创建
    var v = 123;
    function foo(){
        var v = 456;
        function inner(){
            console.log(v);
        }
        return inner;
    }
    var result = foo()
    console.log(result)
    console.log(result())

问输出结果？ 
 ƒ inner(){
            console.log(v);
        }
 456
    
题目2.js面向对象
Name = 'root';
Age = 18;
function Foo(name,age){
    this.Name = name;
    this.Age = age;
    this.Func = function(){
        //this=obj
        console.log(this.Name,this.Age);
        (function(){
            //this=window
            console.log(this.Name,this.Age);
        })();
    }
}
obj = new Foo('alex',666);
obj.Func();

问输出结果？
alex 666
root 18

题目3：作用域
var name = '女神'

function Foo(name,age){
	this.name = name;
	this.age = age;
	this.getName = function(){
		console.log(this.name); # 屌丝
		var that = this 
		(function(){
			console.log(that.name); # 屌丝
		})()
		
	}
}

obj = new Foo(“屌丝”',19)

obj.getName()

题目4：实例化对象
var name = '女神'
obj = {
	name:'屌丝',
	age: 19,
	getName:function(){
		console.log(this.name); # 屌丝
		var that = this 
		(function(){
			console.log(that.name); # 屌丝
		})()
	}
}
obj.getName()