Js词法分析__return [js面试题]

Posted 2022-11-25 脚本叔叔

代码块

<script type="text/javascript">
    function test()
        var a = 12;
        var b = 24;
        console.log('number: ' + number);  //undefined
        return a + b;  //return 后面的语句没有执行,但是会做词法分析
        console.log( a + b );
        var number = 12;  
    
    var c = test();
    console.log( c );//36
</script>

执行顺序

1. 词法分析期
   a=undefined
   b=undefined
   number=undefined
2. 运行期：
   赋值..
   a = 12
   b = 24

输出结果

number: undefined
36