Javascript - need explanation on the variable inside IIFE

Question

I have this code - I just wonder why after I add 'var' to foo variable, it doesn't work (it shows me foo is undefined)... Can anyone help explain these two functions? Thanks!

window.onload = function() {
    var test = foo().steps(2);
    console.log(test);
}

(function() {
  //if I remove var, then it prints out a function which is what I expected
  var foo = function() {
    var steps = 1;
    function callMe(g) {
      //do something else
      console.log("hello" + g);
    }
    callMe.steps = function(x) {
      //if no arguments then return the default value
      if (!arguments.length) return steps;
      console.log(arguments);
      //otherwise assign the new value and attached the value to callMe
      steps = x;
      return callMe;
    }
    return callMe;
  }
})();

Because `var` variables are function-scoped. You use `foo` outside the function it’s declared in. — Sebastian Simon, Dec 14 '15 at 03:49
Possible duplicate of [How do JavaScript closures work?](http://stackoverflow.com/questions/111102/how-do-javascript-closures-work) — Alexander O'Mara, Dec 14 '15 at 04:08
@AlexanderO'Mara the link is really helpful... Thanks though. — catlovespurple, Dec 14 '15 at 04:12

score 1 · Accepted Answer · answered Dec 14 '15 at 03:51

1

adding var to foo makes foo a local variable inside the IIFE and thus you can't access it outside.

answered Dec 14 '15 at 03:51

Ramanlfc

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Can you advise how to expose foo to outside? – catlovespurple Dec 14 '15 at 03:52
1

@catlovespurple Declare `foo` outside the function and define it inside the function. – Sebastian Simon Dec 14 '15 at 03:53
@Xufox can u just write some code to illustrate your suggestion? It's kind of hard to understand exactly what you mean here... – catlovespurple Dec 14 '15 at 03:55
@catlovespurple Have you Googled “javascript variable declaration” or “javascript variable scope” before writing that comment? – Sebastian Simon Dec 14 '15 at 03:56
@catlovespurple declare `var foo;` outside the IIFE and assign foo inside the IIFFE – Ramanlfc Dec 14 '15 at 03:56
@Xufox it's not about if I did Google, it's about your comment is not clear. Now I understand, thanks . – catlovespurple Dec 14 '15 at 03:58

Javascript - need explanation on the variable inside IIFE

1 Answers1