Help

CodingForums
Having trouble with scripting? Visit our help forum to get the answers you need.

Partners
This is a

Using object detection to sniff out different browsers

Since different browsers support different objects, you can use Object Detection as a quick though less than infallible way of detecting various browsers. For example, since only Opera supports the property "window.opera", you can use that to instantly separate an Opera browser from the herd. Here are a few sample test cases, and what they *imply* about the browser running it:

Example objects used to "rough" detect a particular browser
Scheme Description
document.getElementById Detects modern browsers in general, which covers IE5+, Firefox1+, and Opera7+
window.getComputedStyle Detects Firefox1+ and Opera 8+
Array.every Detects Firefox1.5+ (method detection)
window.Iterator Detects Firefox2+
document.all Detects IE4+
window.attachEvent Detects IE5+
window.createPopup Detects IE5.5+
document.compatMode && document.all Detects IE6+
window.XMLHttpRequest Detects IE7, Firefox1+, and Opera8+
window.XMLHttpRequest && document.all Detects IE7. Note: Will fail if visitor explicitly disables native xmlHTTPRequest support (under Toolbar-> Internet Options-> Advanced)
document.documentElement && typeof document.documentElement.style.maxHeight!="undefined" Another way of detecting IE7 that is more reliable than the above.
window.opera Detects Opera (any version).

* Since Opera by default also identifies itself as IE (apart from Opera), with support for many of IE's proprietary objects, the IE detection schemes above will also return true for Opera. Use "window.opera" in combination to filter out Opera browsers.

It's important to mention that object detection's chief purpose is to help you detect within your script whether the browser supports a particular object/method/property before using it, not browser detection. As the later it may be convenient over probing the Navigator object, but is only as reliable as your understanding of which objects are supported in which browsers. In other words, it's not a 100% reliable way of sniffing out the user's browser. Having said that, the below uses object detection to test for IE7:

<script type="text/javascript">
if (document.documentElement && typeof document.documentElement.style.maxHeight!="undefined")
alert("You're using IE7")
</script>

Again object detection is really about feature detection. It detects whether your browser supports the feature your script intends to use and manipulate. For the lazy, that will substitute for browser detection just fine!