javascript - Why can't console.log be called using .call() - Stack Overflow

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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?

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?

• javascript

Share Improve this question Follow edited Aug 18, 2014 at 7:52 idmean 14.9k99 gold badges6161 silver badges8989 bronze badges asked Aug 18, 2014 at 7:48 NigiriNigiri 3,64977 gold badges3232 silver badges5252 bronze badges 5

• 2 @Teemu I think he wants to know why the 2nd yields that error :) – Silviu Burcea Commented Aug 18, 2014 at 7:52
• see more about Function.prototype.call and this keyword – Grundy Commented Aug 18, 2014 at 7:52
• @SilviuBurcea Then why not ask about it? – Teemu Commented Aug 18, 2014 at 7:53
• @Teemu I'm sorry about that.. – Nigiri Commented Aug 18, 2014 at 8:03
• console functions will be bound to console: codereview.chromium/1859293002 – adrianton3 Commented May 2, 2016 at 19:02

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1 Answer 1

Sorted by: Reset to default 11

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.

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