HTML5 compatibility is an important criteria for a mobile device. We compared both iOS5 and iOS6 and their browser support for HTML5 by utilizing an HTML 5 testing site; As expected, the browser on iOS 6.1 gets a much higher score, 386 out of 500, compared to 344 for iOS 5.1.

Total Score386344


Probable Causes For Differences Between iOS 6.1 and iOS 5.1

Let’s first review some sub-scores between these two operating systems which show the most significant improvements of iOS6.1.

Forms (Field Types)10291
Audio(Web Audio API)50
File(File API)100

From the table, we can see that iOS6.1 has more security features and supports more APIs (Web Audio API and File API) and more field types like ‘type=file’ which can directly use files on a web page.

1. For security, iOS 6.1 supports ‘iframe with inline contents’ as shown in the figure below.


An inline frame is a construct which embeds a document into an HTML document so that embedded data is displayed inside a sub-window of the browser’s window. These two documents are totally independent and both are treated as complete documents. There is no ‘inclusion’ relationship between them. With this feature, each document within the HTML5 has its own session and can handle its data separately .

2. Including File API, iOS 6.1 can load local files without uploading the files to any servers. An example of this feature is you can drag an image to a specific area of your iOS 6.1 browser and the image will be displayed.

3. With the HTML5 

4. For Forms Support, the greatest change is that iOS 6.1 supports the input of file which is associated with 2 above. This helps iOS6 score 10 more points.

When testing mobile applications, HTML5 Compatibility will continue to gain increasing importance. Make sure you understand what types of HTML5 compatibility features are important to your application and what browser/OS combinations are most prevalent in your user base.