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  • 482 私有栈内存处理

    闭包:函数执行形成的私有栈内存,会把内存中的所有私有变量都保护起来,和外面没有任何关系,函数的这种保护机制就是闭包

    console.log(a, b);
    var a = 12,
    	b = 12;
    
    function fn() {
    	console.log(a, b);
    	var a = b = 13;
    	console.log(a, b);
    }
    fn();
    console.log(a, b);
    
    


    console.log(a, b, c);
    var a = 12,
    	b = 13,
    	c = 14;
    
    function fn(a) {
    	console.log(a, b, c);
    	a = 100;
    	c = 200;
    	console.log(a, b, c);
    }
    b = fn(10);
    console.log(a, b, c);
    
    


    function sum(a) {
    	console.log(a);
    	let a = 100; // => Uncaught SyntaxError: Identifier 'a' has already been declared
    	console.log(a);
    }
    sum(200);
    

    var ary = [12, 23];
    
    function fn(ary) {
    	console.log(ary);
    	ary[0] = 100;
    	ary = [100];
    	ary[0] = 0;
    	console.log(ary);
    }
    // 注意,这里传递的是全局变量arr保存的地址值,不是传递[12, 23]
    fn(ary);
    console.log(ary);
    
    

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  • 原文地址:https://www.cnblogs.com/jianjie/p/13192951.html
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