Detect IE version (prior to v9) in JavaScript

Return IE version or if not IE return false

function isIE () {
  var myNav = navigator.userAgent.toLowerCase();
  return (myNav.indexOf('msie') != -1) ? parseInt(myNav.split('msie')[1]) : false;
}

Example:

if (isIE () == 8) {
 // IE8 code
} else {
 // Other versions IE or not IE
}

or

if (isIE () && isIE () < 9) {
 // is IE version less than 9
} else {
 // is IE 9 and later or not IE
}

or 

if (isIE()) {
 // is IE
} else {
 // Other browser
}

This is my preferred way of doing it. It gives maximum control. (Note: Conditional statements are only supported in IE5 - 9.)

First set up your ie classes correctly

<!DOCTYPE html>
<!--[if lt IE 7]> <html class="lt-ie9 lt-ie8 lt-ie7"> <![endif]-->
<!--[if IE 7]>    <html class="lt-ie9 lt-ie8"> <![endif]-->
<!--[if IE 8]>    <html class="lt-ie9"> <![endif]-->
<!--[if gt IE 8]><!--> <html> <!--<![endif]-->    
<head>

Then you can just use CSS to make style exceptions, or, if you require, you can add some simple JavaScript:

(function ($) {
    "use strict";

    // Detecting IE
    var oldIE;
    if ($('html').is('.lt-ie7, .lt-ie8, .lt-ie9')) {
        oldIE = true;
    }

    if (oldIE) {
        // Here's your JS for IE..
    } else {
        // ..And here's the full-fat code for everyone else
    }

}(jQuery));

Thanks to Paul Irish.


Use conditional comments. You're trying to detect users of IE < 9 and conditional comments will work in those browsers; in other browsers (IE >= 10 and non-IE), the comments will be treated as normal HTML comments, which is what they are.

Example HTML:

<!--[if lt IE 9]>
WE DON'T LIKE YOUR BROWSER
<![endif]-->

You can also do this purely with script, if you need:

var div = document.createElement("div");
div.innerHTML = "<!--[if lt IE 9]><i></i><![endif]-->";
var isIeLessThan9 = (div.getElementsByTagName("i").length == 1);
if (isIeLessThan9) {
    alert("WE DON'T LIKE YOUR BROWSER");
}

If nobody else has added an addEventLister-method and you're using the correct browser mode then you could check for IE 8 or less with

if (window.attachEvent && !window.addEventListener) {
    // "bad" IE
}

Legacy Internet Explorer and attachEvent (MDN)

Tags:

Javascript

Internet Explorer

Browser Detection

User Agent

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