Hoisting in javascript

问题

I asked a question before and somebody give me a guide and I read it and I saw this

  var temp = setTimeout,
  setTimeout = function() {};

He said that temp will be undefined due to JavaScript hoisting and I dont understand why Its not should be like that?

    var temp;
    temp = setTimeout;
    setTimeout = function() {};

so why its undefined?

回答1:

This is not the same. Your multiple var declaration also declares setTimeout:

var temp = setTimeout,
    setTimeout = function() {};

which is hoisted to

var temp; // = undefined
var setTimeout; // = undefined
temp = setTimeout;
setTimeout = function() {};

来源：https://stackoverflow.com/questions/13505048/hoisting-in-javascript