How can I fool a site that looks at the JavaScript object 'navigator' to see that I'm not on Windows?

Question

I am trying to browse a website, however, it only works under Windows and Mac because they use the navigator.platform from JavaScript to find out the architecture I am running on. Of course, they also use the browser's user agent, but that was easy to spoof.

Here is the .js in question: http://pastebin.com/f56fd608d. The code responsible for browser detection is at the top. Is there any way of changing the .js file before the site runs, or something similar, so I can eliminate the check?

Using the JavaScript console yields:

>navigator.platform
Linux i686

Evidently I changed the browser's user agent, but navigator.platform does not seem to take it's value from the user agent.

Maybe someone knows how to change the value returned by navigator.platform, because I hate running Windows under VirtualBox to use this site.

EDIT: This could be of interest because Linux users might be artificially denied access to websites, and can do nothing about it.

Answer 1

Since you can't directly set navigator.platform, you will have to be sneaky - create an object that behaves like navigator, replace its platform, then set navigator to it.

var fake_navigator = {};

for (var i in navigator) {
  fake_navigator[i] =  navigator[i];
}

fake_navigator.platform = 'MyOS';

navigator = fake_navigator;

If you execute this code before the document loads (using GreaseMonkey, an addon or a Chrome extension), then the page will see navigator.platform as "MyOS".

Note: tested only in Chrome.

Answer 2

var fakePlatformGetter = function () {
  return "your fake platform";
};
if (Object.defineProperty) {
  Object.defineProperty(navigator, "platform", {
    get: fakePlatformGetter
  });
} else if (Object.prototype.__defineGetter__) {
  navigator.__defineGetter__("platform", fakePlatformGetter);
}

Answer 3

about:config - > general.platform.override

Answer 4

For a Mozilla-based browser, GreaseSpot / Code Snippets # Hijacking browser properties demonstrates how it may be done. This code may be injected from a GreaseMonkey script.

Answer 5

Provided that the browser you're using supports Object.defineProperty() (it likely does), a more modern way of achieving the same goal is as follows:

Object.defineProperty(navigator, 'platform', {
  value: 'my custom value',
  configurable: true // necessary to change value more than once
});

This allows you to set it to any custom value you want, and it also allows you to change it as many times as you want without needing to reload the page.

Answer 6

Attempting to change this property (at any time) in Firefox yields:

Error: setting a property that has only a getter

Source File: index.html

Line: 1

So I think you will have a hard time.

I'd try to contact the author about obtaining a fix.