函数声明与变量声明

•    function change(){
          console.log(typeof fn)//function
          function fn(){}
          var fn =1；
          //var fn;与fn=1；效果一样
      }
      change()
  //变量声明上述代码等于,
     function change(){
          function fn(){}
          var fn ；
          console.log(typeof fn)//function
           fn = 1;
      }
      change()    
  

  function change(){
      function fn(){}
      var fn =1;
      console.log(typeof fn)
  }
  change()//number因为赋了值就覆盖了fn()

  function change(){
      function fn(){}
      var fn;
      console.log(typeof fn)
  }
  change()//function,未赋值所以不能覆盖