lovecoding
/
Web1020


			
				
					
						
						
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							<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <ul>
        <li>1</li>
        <li>2</li>
        <li>3</li>
        <li>4</li>
        <li>5</li>
        <li>6</li>
    </ul>
    <script>
        var aLi = document.getElementsByTagName('li');
        for(let i=0;i<aLi.length;i++){
            // aLi[i].index = i;
            aLi[i].onclick = function(){
                console.log(i);
            }
        }
        
        // var a = 10;
        // function foo(){
        //     console.log(++a);
        // }

        // foo();
        // foo();
        // 闭包 当出现多重作用域嵌套时候，内部函数调用外部函数的局部变量 变量就不会被释放
        function foo(){
            var a = 10;
            function foo2(){
                console.log(++a);
            }
            return foo2;            
        }

        var f = foo();
        f();
        f();
    </script>
</body>
</html>