FAQ Topic - How do I detect Opera/Safari/IE? (2010-08-14)
in [JavaScript]
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From: FAQ server on 13 Aug 2010 19:00 ----------------------------------------------------------------------- FAQ Topic - How do I detect Opera/Safari/IE? ----------------------------------------------------------------------- The short answer: _Don't do that_. The `navigator` host object contains properties which may identify the browser and version. These properties are historically inaccurate. Some browsers allow the user to set `navigator.userAgent` to any value. For example, Firefox, (type `about:config` and search `useragent` or Safari, `Develop > User Agent > Other...`, IE, via Registry. Other browsers, such as Opera, provide a list of user agents for the user to select from. There are also at least 25 other javascript capable browsers, with multiple versions, each with their own string. Browser detection is unreliable, at best. It usually causes forward-compatibility and maintenance problems. It is unrelated to the problem or incompatiblity it is trying to solve and obscures the problems it is used for, where it is used. Object detection is checking that the object in question exists. http://dev.opera.com/articles/view/using-capability-detection/ goes one step further to actually test the object, method, or property, to see if behaves in the desired manner. Feature Test Example: /** * Returns the element/object the user targeted. * If neither DOM nor IE event model is supported, returns undefined. * @throws TypeError if the event is not an object. */ function getEventTarget(e) { e = e || window.event; // First check for the existence of standard "target" property. return e.target || e.srcElement; } <URL: http://jibbering.com/faq/notes/detect-browser/> <URL: http://dev.opera.com/articles/view/using-capability-detection/> <URL: http://developer.apple.com/internet/webcontent/objectdetection.html> <URL: http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.43> The complete comp.lang.javascript FAQ is at http://jibbering.com/faq/ -- The sendings of these daily posts are proficiently hosted by http://www.pair.com. |