What's the difference between isPrototypeOf and intanceof in Javascript?

Posted by Steffen Heil on Stack Overflow See other posts from Stack Overflow or by Steffen Heil
Published on 2010-03-17T17:28:45Z Indexed on 2010/03/17 17:31 UTC
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JavaScript

|

prototype

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instanceof

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inheritance

Hi

In some of my own older code, I use the following:

Object.prototype.instanceOf = function( iface )
{
 return iface.prototype.isPrototypeOf( this );
};

Then I do (for example)

[].instanceOf( Array )

This works, but it seems the following would do the same:

[] instanceof Array

Now, surly this is only a very simple example. My question therefor is:

Is a instanceof b ALWAYS the same as b.prototype.isPrototypeOf(a) ?

Regards, Steffen

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