Change window.location prototype to disable certain redirects?

Question

I'm trying to selectively disable window.location, using Greasemonkey, at the start of the document.

I don't want to fully disable javascript, just disable some redirects done with javascript. They look like this:

window.location = "unwanted url";

Answer 1

I don't think it's possible.

• You can't overwrite properties or methods on window.location (fails silently)
• you can't redefine its prototype with location.__proto__ = Something.prototype
• location.constructor.prototype is basically Object.prototype
• the constructor doesn't really do anything (like create the attributes or methods)
• __definesetter__ fails silently
• Object.defineProperty gives an error like, TypeError: Cannot redefine property: href
• delete window.location and delete window.location.href don't do anything

I'm out of ideas...

Answer 2

You can't change the window.location prototype, because this a "native property" of window and it is not configurable.

On Firefox (Greasemonkey), if you try to override this then you will get errors like:

TypeError: can't redefine non-configurable property 'location'

and

Error: Permission denied to shadow native property

...depending on how you attempt it. Other browsers give similar errors.

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To block this kind of relocation, you need to interfere with the page's javascript on a case-by-case basis.

See "Stop execution of Javascript function (client side) or tweak it" for a general approach that works in Firefox. Although it may be much easier, depending on your target page's exact code.