Detection of Browsers not compatible

When you see websites that contain messages or even disallowing use of a particular browser, is that code in PHP, ASP.NET, etc or is that JS? I am specially talking about websites that disallow IE 11 where they indicate to use Edge, Chrome or FF.

Thank you

My understanding is that designers frequently offer to support IE11 for $XXX.00 extra dollars, and the client refused to pay that much.

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I appreciate that, but what I was asking is that detection of, let’s say IE11 and then denial of that browser JS code?

What do you think is a more appropriate behavior when you aren’t being paid to support IE11?

If I knew I wouldn’t be asking the question. Thanks anyway!

There are many things that work in most other browsers, but don’t work in Internet Explorer.
Frequently supporting Internet Explorer results in a worse experience, and a lot more extra work.

Developers and designers must spend more time to get things working in Internet Explorer, and frequently must cancel other website plans when needing to support less-capable web browsers.

Not many people want to do that extra work for free, so you’re left with a situation of deciding which browsers get full support, which get partial support, and others that get no support.

The question wasn’t about the whys though, Paul. It was about the mechanics of how.

The sites can use either form of technology (client side or server side) to attempt this. Mostly it will key off of the Agent sent with the browser’s request from the server side. The client side has a bit more flexibility, such as testing for the existence (or non-existence) of certain key functions/functionality that can determine (more reliably) the browser being used.

The whys are mostly as Paul says - Microsoft has never complied with standards unless it suits their whims; they develop their own versions of many things, causing developers who want (or as Paul indicates, are paid for) universal functionality to develop code that exists in two parts - “Microsoft”, and “Everybody else.”


When it comes to browser detection for JavaScript, that is normally frowned upon as there is no guaranteed way to correctly identify any given web browser.
We tried doing browser detection and things failed when the next version of a web browser came out.

Because of such issues, we moved to feature-detection instead. That way if a browser doesn’t support a certain feature, we just don’t run the code that uses that feature. The browser misses out, but that’s about the worst of it.

Here’s a useful article with more details about this:


Both. Server application and also JS able to select current browser. Which way uses some resource developer - who knows…

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Fully aware of that which is why I am trying to move away from that support; hence the question.

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