Stefan Kendall Stefan Kendall - 1 month ago 10
Javascript Question

Mocking a useragent in javascript?

I'm looking for a way to programmatically change navigator.userAgent on the fly. In my failed attempt to get an automated javascript unit tester, I gave up and attempted to begin using fireunit. Immediately, I've slammed into one of the walls of using an actual browser for javascript testing.

Specifically, I need to change navigator.userAgent to simulate a few hundred userAgent strings to ensure proper detection and coverage on a given function. navigator.userAgent is readonly, so I seem stuck! How can I mock navigator.userAgent? User Agent Switcher (plugin) can switch FF's useragent, but can I do it within javascript?

Answer

Try:

navigator.__defineGetter__('userAgent', function(){
    return 'foo' // customized user agent
});

navigator.userAgent; // 'foo'

Tried it in FF2 and FF3.

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