How can you detect the version of a browser?

Question

I\'ve been searching around for code that would let me detect if the user visiting the website has Firefox 3 or 4. All I have found is code to detect the type of browser but

Answer 1

In pure Javascript you can do a RegExp match on the navigator.userAgent to find the Firefox version:

var uMatch = navigator.userAgent.match(/Firefox\/(.*)$/),
    ffVersion;
if (uMatch && uMatch.length > 1) {
    ffVersion = uMatch[1];
}

ffVersion will be undefined if not a Firefox browser.

See working example →