What is preferable : detecting device using its size or user agent string?

Question

I need to differentiate between mobile/tablet and desktop browsers and i was wondering is it better to parse user agent string or look at width and height of the device to determine same? Which method is preferable and why?

TIA

Answer 1

You typically need to do both. The User Agent isn't enough to distinguish between android phones and tablets.

See this link on how Google Web Toolkit does it: https://code.google.com/p/google-web-toolkit/source/browse/trunk/samples/mobilewebapp/src/com/google/gwt/sample/mobilewebapp/FormFactor.gwt.xml?r=10041

Basically, you check the useragent for "iphone" or "ipad", else check for "android" (if so, use the size to determine mobile/tablet), otherwise it's a "desktop".

Answer 2

Is this information directly used by your application, or is it used by business/marketing to figure who is looking at your site? If it is a marketing need, then you should use Google Analytics, you simply embed a piece of code into your HTML and your business folks will get ALL the info they'd ever want about visitor's devices, browsing patterns, drop off pages, flows, etc.