JavaScript作用域与作用域链

古城微笑少年丶 2023-10-06 17:44 40阅读 0赞

## 其实还是this指向规则问题 ##

1、

var x = 10;
    
    function fn() {
        
    	console.log(x);
    }
    
    function show(f) {
        
    	var x = 20;
    	f();
    }
    
    show(fn);//10

2、

var fn = function() {
        
    	console.log(fn);
    }
    
    fn()
    
    var obj = {
        
    	fn2: function() {
        
    		console.log(fn2);
    	}
    }
    obj.fn2()

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NTA4NDk4Ng_size_16_color_FFFFFF_t_70]

var fn = function() {
        
    	console.log(fn);
    }
    
    fn()
    
    var obj = {
        
    	fn2: function() {
        
    		console.log(this.fn2);
    	}
    }
    obj.fn2()

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NTA4NDk4Ng_size_16_color_FFFFFF_t_70 1]  
3、

var num1=12;
    var num2=13
    
    function fun(num,num1){
        
    	/*
    	var num;
    	var num1;
    	*/
    	num=100;
    	num1=100;
    	num2=100;
    	console.log(num);
    	console.log(num1);
    	console.log(num2);
    }
    
    fun(num1,num2);
    console.log(num1);
    console.log(num2);
    console.log(num);

![在这里插入图片描述][20210606112013272.png]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NTA4NDk4Ng_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/20210523111208699.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NTA4NDk4Ng==,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NTA4NDk4Ng_size_16_color_FFFFFF_t_70 1]: https://img-blog.csdnimg.cn/20210523111228771.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NTA4NDk4Ng==,size_16,color_FFFFFF,t_70
[20210606112013272.png]: https://img-blog.csdnimg.cn/20210606112013272.png