Question

How to compare browser versions via javascript?

For example if script wants to know if user is using Firefox 3.5+

Is there any way?

Answer 1

This code gets the version number of Firefox:

var FFVersion = navigator.userAgent
                  .substring(navigator.userAgent.indexOf("Firefox"))
                  .split("/")[1];

You decide what to do with each of them:

window.onload = function() {
    if (FFVersion < '3.5') { alert('please upgrade...') }
}