901723 - Uint8Array prototype is not extensible.

Status: RESOLVED DUPLICATE of bug 695438

(Core :: JavaScript Engine, defect)

Description

[adam]

User Agent: Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/28.0.1500.72 Safari/537.36

Steps to reproduce:

Create a simple script:

Uint8Array.prototype.read = function () {
  this.start = 5;
  console.log(this.start); // variable undefined
};

Also:
Uint8Array.prototype.start = 5;
Uint8Array.prototype.read = function () {
  this.start = 6;
  console.log(this.start); // prints 6
};

The same happens with Object.defineProperty(Uint8Array.prototype, ...


Actual results:

this.start behaves as an immutable variable, you can't assign a value to it.


Expected results:

It should get the correct value or raise an error (at least in strict mode).

Comment 1

[Boris Zbarsky [:bzbarsky]]

Isn't this just bug 695438?  In particular, it's the _instances_ that are not extensible, not the prototype, no?

Comment 2

[adam]

You are right, this seems to be a duplicate, they describe the very same behavior.
But how can I add a custom property to every Uint8Array? Do I have to create a wrapper object?

Comment 3

[Till Schneidereit [:till]]

Yup, this is a duplicate of bug 695438. Once that is fixed, defining a getter/setter will work.