Variable not holding reference to `this`

Question

function test1() {
  this.name = 'test1';
  var that = this;

  function test2() {
    this.name = 'test2';
    console.log(that.name);
  }

  test2();
}

test1();

When this executes, I expect the console to log out test1. Why do I get test2 instead? I expect the that variable to hold a reference to the test1 function.

Because `that` and both `this`es point to the global object `window`. You're not creating an instance (using `new`) so that the `this` (of `test1`) will be that instance, you are just calling the functions directly. — ibrahim mahrir, May 27 '18 at 02:03
Try: `var a = new test1();` Or just `new test1();` (for short). — ibrahim mahrir, May 27 '18 at 02:05
Possible duplicate of [How does the "this" keyword work?](https://stackoverflow.com/questions/3127429/how-does-the-this-keyword-work) — Isaac, May 27 '18 at 02:32
*"that variable to hold a reference to the test1 function."* That isn't what "this" or "that" are in JavaScript. They don't hold references to functions, they hold object references. — user229044, May 27 '18 at 03:46

Chiran K. · Answer 1 · 2018-05-27T03:10:01.753

1

Your variable that becomes an object reference since you assign keyword this to it. That means the variable that will be an object and it will have a reference to this(that is, the current object).

Further, the variable that is not a value type. It is an object.

For more on this, search on " value type vs reference types ".

Hope this helps.

edited May 27 '18 at 03:10

answered May 27 '18 at 02:56

Chiran K.

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3
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score 0 · Answer 2 · answered May 27 '18 at 04:09

In a function definition, this refers to the "owner" of the function. Please find the description in inline comments. Rearranging your code according to the order of execution,

test1();                      //Now this is called by window object
function test1() {
  this.name = 'test1';        //window.name = 'test1';
  var that = this;            //that is also now window obj
  test2();                    //this.test2 or window.test2()
  function test2() {
    this.name = 'test2';      //window.name is now test 2
    console.log(that.name);   //since in third step, that is window, that.name or window.name is now test 2
  }
}

Variable not holding reference to `this`

2 Answers2