Question

With the following code, how can the method my_method be called so that it prints the global object (window) ?

 MyClass = function() {
      this.my_method = function() {
         console.log(this);
      }
  }
  var myobject = new MyClass();

This is not an homework, but a question that I’ve been asked and that I can’t understand because i don’t know in deep JavaScript.

So, if someone can help me understand and give me a well explained answer I will be happy !

Answer 1

You can bind the function to null :

MyClass = function() {
      this.my_method = function() {
         console.log(this);
      }
  }
  var myobject = new MyClass();
  myobject.my_method = myobject.my_method.bind(null);
  myobject.my_method(); // this will log the DomWindow object

That’s because when the context of a function is null or undefined, this is the global object.

From the ECMAScript reference :

1. If the function code is strict code, set the ThisBinding to thisArg.
2. Else if thisArg is null or undefined, set the ThisBinding to the global object.