Differences between Express v3 and Express v4

Express Detection v4 uses our new, more comprehensive, detection engine. This features staged detection system which means we can detect iPhones, detect iPads and any devices that use the same HTTP headers for a family of devices.

There are a few differences between v3 and v4 which apply to all scripts directly accessing the HandsetDetection object. If you're using our rule builder for redirects then you can safely ignore this article :)

The three main differences are :

1) The calling URL is different

v3 Uses :


v4 Uses :


Where XXXXX is your site id.


2) In v3 the main object was called HandsetDetection, in v4 this object has been renamed to hdRequestObject.


3) In v3 you could call the detection script synchronously first then place your own Javascript snippet after that and access the object. This is no longer a supported way to access the detection information. In v4 wrap your redirect, call outs or custom scripting inside a function called hdLocalRedirect which you place in the <head> before call to the detection script.


Other minor differences are

- We've added ppi, aliases and displaysize as object properties.


Express v3 will continue to be supported - we have no plans to retire it.

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