Add a JavaScript getter/setter to a native unconfigurable property

Question

I am using special getter/setters to intercept changes made to properties of an object, and it currently works great for any normal user-defined properties. However, I would love if I could employ the same idea to built-in properties like HTMLInputElement.value or Array.length, but these are unfortunately defined as unconfigurable and thus I get an error when attempting to redefine them using a getter/setter.

I'm just wondering if there's any kind of (reliable) hack that I can do to force these to be redefined without breaking their internal operation.

If not, I'll probably be forced to define alternate properties for all of these that simply map to the native properties and use them instead, but that's just so not ideal.

score 0 · Answer 1 · answered Feb 07 '12 at 17:59

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Work with JavaScript 1.8.1 on later : Defining getters and setters

answered Feb 07 '12 at 17:59

Alexis Delrieu

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André Alçada Padez · Answer 2 · 2012-02-07T17:05:41.390

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that is not in any way a good practise, but if you really need to, those functions are defined on the prototype level so:

Array.prototype.length = (function(){})();

Ok, i think even this approach doesn't work with some functions, they must be protected

edited Feb 07 '12 at 17:05

answered Feb 07 '12 at 16:50

André Alçada Padez

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Yeah exactly, they're defined as unconfigurable, meaning you can't change their definition. Was just curious if there was a way around it. – devios1 Feb 08 '12 at 15:12
[].length is *not* a function. – Michael Dec 31 '14 at 16:01

Add a JavaScript getter/setter to a native unconfigurable property

2 Answers2