变量提升

No1，变量提升。No2，函数声明提升（全部升上去）

 (function(a){
        //var a;
        //var a = 100;
        //var a = fn
        var a=10;
        function a(){};
        console.log(a);
    }(100));

var a = 10;
function a(){
  console.log(a);
}
 console.log(a);//10

console.log(a);//fn
var a = 10;
function a(){
  console.log(a);
}

    foo();//1
    console.log(foo);//fn
    function foo(){
        console.log(1);
    }
    var foo = function (){
        console.log(2)
    };

 function fn(bar){
      console.log(bar);//5    形参相当于js内部自动进行的var声明  var bar = 5;
      var bar = 1;
 }
 fn(5);

  function fn(bar){
        console.log(bar);
        var bar = 1;
        function bar(){
            return'函数1';
        }
    }
    fn(5);