Question about 'this'

1

Why does ‘this’ point to the global obj in this code:

function display(){
 console.log(this); // 'this' will point to the global object
}

display();

But to the local object in this code:

var obj = {
 name: 'Saurabh',
 display: function(){
   console.log(this.name); // 'this' points to obj
  }
};

obj.display(); // Saurabh

Also what is a context object?

Thanks,

Andrej

2

This guy does a pretty good job of explaining it:

1 Like
3

This:

function display () {
 console.log(this);
}

Is basically this:

globalThis.display = function () {
  console.log(this.name);
};

So if you compare the other function:

var obj = {
  name: 'Saurabh',
  display: function () {
    console.log(this.name);
  },
};

this, the calling context, is the object to the left of the dot. obj.display – obj is to the left of the dot. globalThis.display – globalThis is to the left of the dot.

In the first example, the calling context is the object globalThis, which will, in a browser, normally (but not always) be an object called window.

In the second example, it’s an object called obj.

So when the code calls console.log, first example tries to resolve globalThis.name, second one tries to resolve obj.name.

1 Like