JavaScript setInterval not being properly bound to correct closure

Question

Problem

Hi people, I\'m reasonably new to JavaScript and I come from the very object-oriented world of Python and Java, that\'s my disclaimer.

There are two ch

Answer 1

You lose your context of Foo in the setInterval callback. You can use Function.bind to set the context to something like this to set the context for the callback function reference back to Foo instance.

setInterval(this.printSomething.bind(this), 3000);

With the call

setInterval(this.printSomething, 3000);

The callback method gets the global context (window in case of web or global in case of tenants like node) so you don't get property bar there since this refers to the global context.

Fiddle

or just

 this.printSomething = function() {
     console.log(bar); //you can access bar here since it is not bound to the instance of Foo
  }