scope of this in self-executing function

Question

Can anybody tell why the global scope is not applicable in the following case ? Why does the line#6 print undefined ? Shouldn't the outer "this" be available in the inner self-executing function ?

var myObj = {
  test1 : 4,
  func : function(){
    console.log(this.test1); //prints 4
    (function(){
      console.log("From self-executing function : " + this.test1); //prints undefined
    })();
  }
};

myObj.func();

Where as, in the following case the global scope is working fine. test1 declared in outer scope is perfectly available in the inner function.

var test1 = 10;
    (function(){
      console.log("From self-executing function : " + test1); //prints 10
    })();

Can anyone please explain what I am missing to understand here ?

Something to do with function in the function, you would need to pass this to the second. Don't know why specifically.. — Matthew Page, Jan 20 '19 at 19:31
@FZs ... well tried that and it says "[object Window]" for the "this" inner function but couldn't understand why so ? why the outer scope in this case not active ? — sandy, Jan 20 '19 at 19:35
You call `func` on `myObj`, so `this` is `myObj` in `func`. You call the inner function on nothing, and it's not bound, so in the inner function, `this` is the global `window` object in non-strict mode, or `undefined` in strict mode. — Paul-Louis Ageneau, Jan 20 '19 at 19:45

Paul-Louis Ageneau · Answer 1 · 2019-01-20T19:40:00.587

0

In the inner function, this refers to the global object (if not in strict mode).

You could modify the code like this to achieve the result you expect:

var myObj = {
  test1 : 4,
  func : function(){
    console.log(this.test1);
    var self = this;
    (function(){
      console.log("From self-executing function : " + self.test1);
    })();
  }
};

myObj.func();

edited Jan 20 '19 at 19:40

answered Jan 20 '19 at 19:33

Paul-Louis Ageneau

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scope of this in self-executing function

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