Why can't console.log be called using .call()

Question

The below code returns a pop-up window with 'hello'.

alert.call(this, 'hello');

But the below code returns an error "TypeError: Illegal invocation".

console.log.call(this, 'hello');

What is the difference in the implements of alert and console.log?

Answer 1

alert is a global method (window.alert). If you call it alert.call(this), this is the window object.

Because log is a method in the console object, it expects this to be the console object itself, but you are still calling it with this(window), so you get an error.

Running console.log.call(console, 'test') will work fine.