5.函数和变量

   var num=10;
    function num(){
        console.log("hello world");
    }
    console.log(num);   //10

        ![image.png](https://cdn.nlark.com/yuque/0/2021/png/22615031/1632878989204-90d704f4-994d-4f3f-9299-de2f5254dd12.png#clientId=u168d1c82-b332-4&from=paste&height=151&id=u5a70e07e&margin=%5Bobject%20Object%5D&name=image.png&originHeight=302&originWidth=674&originalType=binary&ratio=1&size=10052&status=done&style=none&taskId=u9578815e-03ed-47b8-88ce-fe79a2bb348&width=337)

 function num(a){
     //var a=20
     console.log(a);
     var a=10;
    function a(){
       console.log("hello world");
   }
      console.log(a);
 }
   num(20);