check version of browser

Question

How can i find what version of browser a user is using and ask him to upgrade it

• Nick Craver: You can use the user agent, which can be spoofed, and alert them...but it depends what you're after, why do they need to upgrade? Is there a feature they need that their current one doesn't support? In that case you should check for that feature's presence.
• andrew Sullivan: how can i check whether the user browser supports that feature or not.
• Nick Craver: same: That depends :) Which feature are you looking for? Flash support, opacity support, CSS3 selctors, something else?
• ANeves: @NickCraver in my case, I want to tell them to update from IE7. >:( They don't know that their browser is outdated, and it's not their responsibility to know because they are institutional users who are not allowed to control the software they use; but I can tell them it's outdated, so that they bother their sysadmins. :)

Answer 1

You can perform feature detection using jQuery, like this:

if (!jQuery.support.opacity)
 //Waah waah waah...

You can also check the browser version using jQuery, like this:

if (!jQuery.browser.msie && jQuery.browser.version === 6)
 //Waah waah waah...

However, it should be avoided where possible.

Answer 2

You can read the HTTP_USER_AGENT from the Request.ServerVariables.

In ASP.NET that would be:

Response.Write(HttpContext.Current.Request.ServerVariables["HTTP_USER_AGENT"]);

More info here

Answer 3

If you are already using a javascript library like jQuery or mootools, you also have those tools at your disposal.

jQuery:

if( $.browser.msie ) {
 // do something
}

mootools:

if (Browser.Engine.trident4) {
 // ie6
}

keep in mind this is usually the wrong thing to rely on. Even the jQuery documentation has a warning that recommends feature detection instead of browser detection.

Answer 4

If it's only about Internet Explorer, you can use conditional comments:

<!--[if IE 6]>
Special instructions for IE 6 here
<![endif]-->

More info at http://www.quirksmode.org/css/condcom.html

Answer 5

On the server-side code: Request.Browser returns a HttpBrowserCapabilities instance with all the information you're looking for.

http://msdn.microsoft.com/en-us/library/system.web.httpbrowsercapabilities.aspx

On the client script side (javascript):

http://www.quirksmode.org/js/detect.html

Further to @Nick's comment, the following MSDN post:

http://msdn.microsoft.com/en-us/library/x3k2ssx2.aspx

states:

Browser capabilities indicate whether the browser type in general supports features such as JavaScript, not whether an individual instance of the browser has these features enabled or disabled.

I think version and type of the browser will tend to be fairly consistent.

• Nick Craver: Browser Abilities depends on that info being up to date, which often is not the case, not at the rate browsers advance.

Answer 6

javascript:
 alert(navigator.appVersion)