updated in 2010

How to detect IE

Push the Internet Explorer users to switch to Firefox. Just copy the HTML snippet or the PHP script into your webiste or blog. This warning is invisible to readers using another browser.

Optionally check if the browser is compatible with your web app. You can check the evolution of browser stats here.

Less IE please

Webmasters are tired of supporting Internet Explorer 6 or 7. Therefore you could stop the support of IE6 in your CSS files. Also do your users a favour and give them an alternative.

Not more Google please

Chrome lighter
reignites a browser war

The means to Web domination include owning the dominant search engine and controlling most of the web browsers. This in turn is done by promoting their own browser (Chrome) and by contracting with Mozilla: by default the Firefox search box triggers the Google engine. So please give the Mozilla foundation the means to stop their contract with Google. You can do that by promoting the use of Firefox -- rather than that of Chrome.

HTML snippet

You can add HTML to any web page. A proposal to switch shows only to users of older IE versions:

<!--[if lt IE 8]> You are using an unsafe, slow, outdated web explorer. You may consider installing an <a href="http://www.mozilla.com/firefox/">alternative <br><img src="/images/firefox-icon.png" align="middle" border="0" height="16" width="16"></a> <![endif]-->

There is no need to detect Chrome Frame if Chrome Frame activates automatically. The trick is to combine the above Internet Explorer conditional comments with the Chrome meta-tag: <meta http-equiv="X-UA-Compatible" content="chrome=1" />. Chrome Frame detects the Chrome meta-tag; thus the page is rendered by Trident, but by WebKit.

This snippet is simple but less flexible than the PHP script further down -- which also checks for Chrome Frame.

What the scripts do

I have created both a HTML snippet and a PHP script that pushes users to switch to a relevant browser. They work as follows:

1. A user triggers her browser to ask for your page (across the Web).

2. The page served is different depending on the user agent. A message only shows on the web page only if the client uses a "bad" browser. The piece of code detects the browser used and displays an upgrade message only if the browser version is bad.

3. The message can be anything. By default it proposes to switch to Firefox. You can choose what you consider bad by editing the $announcement between the simple quotes on line 15 in the PHP script below.

PHP code for detecting IE and Chrome Frame

Die Internet Explorer!

If you do not have a Wordpress blog, please use my PHP code herebelow. You can insert it into most HTML files.

<?php // Die IE! a script by Félicien Breton, at www.frenchscout.com, licensed under the GPL v3 ################################################## # Display a call to change browser if not webapp-capable ################################################## function die_ie($default_statement='') { global $language; // The announcement depends on the page language -- not on the browser language<br> if ( $language=='fr' ) { $announcement = 'Vous utilisez un navigateur internet qui n’est ni fiable, ni rapide.<br>Envisagez une <a class="external" href="http://www.mozilla.com/firefox/">alternative'; } else { $announcement = 'You are using an unsafe, slow, outdated web explorer.<br>You may consider installing an <a class="external" href="http://www.mozilla.com/firefox/">alternative'; } $announcement .= '.<br><img src="/images/firefox-icon.png" align="middle" border="0" height="16" width="16"></a>'; // We test the user browser and the presence of the Chrome Frame plug-in if ( stristr($_SERVER['HTTP_USER_AGENT'], 'chromeframe') ) { return $default_statement; } elseif ( strstr($_SERVER['HTTP_USER_AGENT'], '; MSIE 5') ) { return $announcement; } elseif ( strstr($_SERVER['HTTP_USER_AGENT'], '; MSIE 6') ) { return $announcement; } elseif ( strstr($_SERVER['HTTP_USER_AGENT'], '; MSIE 7') ) { return $announcement; } elseif ( strstr($_SERVER['HTTP_USER_AGENT'], '; MSIE 8' ) ) { return $default_statement; } else { return $default_statement; } } # end of function // Trigger the function $language='en'; echo die_ie(':-)'); ?>

Note on Chrome Frame: you may simplify the script by removing the test of Chrome Frame. The above implementation considers that the user have their own idea about which browser to use if they have installed Chrome Frame. Most IE6 users are trapped within that browser because the Intranet applications on their corporate network do not work in any other browser -- not even IE7.

This script issues a warning to only those clients who cannot use your webapp -- I mean a website who would use a snappy (AJAX) user interface.

You may reuse and propagate this script with either one of two licenses:

• the MPL v1.1 (which is weak copyleft or weak viral);
• the latest GPL license (which is strong copyleft or strong viral).

This alternative allows the use of the "Die IE!" code in a variety of software projects, while still maintaining copyleft on the said code. So choose the license and adapt the code to your needs. Usage: launch an editor, open your HTML or PHP file, copy and paste the above script, change the French detection (on line 11) to your own language (if not English).