Recently I’ve been spending a fair amount of time working on HTML-based applications – both mobile web and mobile applications using PhoneGap. Regardless of whether you are targeting a mobile web browser or a mobile app using the PhoneGap container, you are still targeting a mobile web browser instance. If you haven’t noticed, mobile web browsers can often have peculiarities with how content is rendered, or how you interact with that content. This happens regardless of platform – iOS, Android, BlackBerry, etc… All have quirks. Here are a few tips that I have found useful for improving overall interaction and mobile HTML experiences.
Disclaimer: I’ve been targeting iOS and Android primarily, with BlackBerry support on some applications. I don’t have a Windows Phone device to test with, so I can’t comment on support for the Windows platform.
AutoCorrect and AutoCapitalize
First things first: autocorrect and autocapitalize on Apple’s iOS can sometimes drive you to the brink of insanity. This is especially the case if you have a text input where you are typing in a username, and it keeps “correcting” it for you (next thing you know, you are locked out of the app). You can disable these features in web experiences by setting the “autocorrect” and “autocapitalize” attributes of an <input> instance.
[html]<input type="text" autocorrect="off" autocapitalize="on" />[/html]
[html]<input type="text" autocorrect="on" autocapitalize="off" />[/html]
Managing the Keyboard
Have you ever experienced an an app or web site on a mobile device where you have to enter numeric data, and the default keyboard pops up. Before entering any text, you have you switch to the numeric input. Repeat that for 100 form inputs, and try to tell me that you aren’t frustrated… Luckily, you can manage the keyboard in mobile HTML experiences very easily using HTML5 Form elements.
Default Keyboard: Supported Everywhere [html]<input style="width: 400px;" type="text" value="default" />[/html]
Numeric Keyboard: Supported on iOS, Android & BlackBerry (QNX) [html]<input style="width: 400px;" type="number" value="numeric" />[/html]
Numeric Keyboard: Supported on iOS [html]<input style="width: 400px;" type="text" pattern="[0-9]*" value="numeric" />[/html]
Phone Keyboard: Supported on iOS [html]<input style="width: 400px;" type="tel" value="telephone" />[/html]
URL Keyboard: Supported on iOS & BlackBerry (QNX) [html]<input style="width: 400px;" type="url" value="url" />[/html]
Email Keyboard: Supported on iOS & BlackBerry (QNX) [html]<input style="width: 400px;" type="email" value="email" />[/html]
Disable User Selection
One way to easily determine that an application is really HTML is that everything on the UI is selectable and can be copied/pasted – Every single piece of text, every image, every link, etc… Not only is this annoying in some scenarios (and very useful in others), but there may be instances where you explicitly don’t want the user to be able to easily copy/paste content. You can disable user selection by applying the following CSS styles. Note: This works on iOS, and partially works on BlackBerry/QNX for the PlayBook. It did not work on Android in my testing.
The -webkit-touch-callout css rule disables the callout, and the -webkit-user-select rule disables the ability to select content within an element. More details on webkit css rules from the Mobile Safari CSS Reference. More detail about disabling copy/paste on iOS is available at StackOverflow.com.
If you want your content to feel like an app instead of a web page, then I strongly suggest that you disable gestures for pinch/zoom and panning for all use cases where pinch/zoom is not required. The easiest way to do this is to set the viewport size to device-width and and disable user scaling through the HTML metadata tag.
[html]<meta name="viewport" content="width=device-width, user-scalable=no" />[/html]
On a Phone? Integrate With It
Your application can dial phone numbers very easily. Just use a standard web location, but use the “tel:<phonenumber>” URI format.
Test it with Apple Customer Support: 800-275-2273[html]<a href="tel:800-275-2273">800-275-2273</a>[/html]
Touch Based Scrolling
Touch-based scrolling is critical to having an application that feels native. I dont mean that the whole page should be able to scroll… Your browser will be able to take care of that alone. Instead I mean that you should be able to scroll individual elements so that they mimic clipped views, lists, or large blocks of content. You should be able to scroll content where it is, and not have to scroll an entire page to reveal something in only one area of the screen. You should minimize scrolling when it may cause poor UX scenarios. This is especially the case in tablet-based applications which have a larger UI than phone-based applications.
Remove “click” Delays
“Click” events on HTML elements on mobile devices generally have a delay that is caused by the operating system logic used to capture gestural input based on touch events. Depending on the device, this could be 300-500 MS. While this doesn’t sound like much, it is very noticeable. The workaround is to use touch events instead of mouse events: touchStart, touchMove, touchEnd. You can learn more about touch events from html5rocks.com. There’s also a great script from cubiq that adds touch events for you to optimize the experience for onClick event handlers on iOS devices.
Add To Home Screen
If you want your web app to fee like a real app and take up the full screen without using PhoneGap as an application container, then you can always add it to the device’s home screen. Although this can only be done manually through the mobile browser, there are a few open source scripts to guide the user through this processs: cubiq.org or mobile-bookmark-bubble should get you started.
Use Hardware Acceleration
Animations will generally be smoother and faster if your content is hardware accelerated (and the device supports hardware acceleration). You can make html elements hardware accelerated just by adding the translate3d(x,y,z) css style to the element (be sure to set all three x, y, and z attributes otherwise hardware acceleration may not be applied. If you don’t want any translation changes, you can use the translate3d CSS rule with all zero values: translate3d(0,0,0).
In your development/testing, you can even visualize which content is hardware accelerated in both desktop and mobile Safari using the technique shown at http://mir.aculo.us/.
Make You Apps Fast
Last, but certainly not least, make your apps fast. Follow best practices, and be efficient in code execution and the loading of assets (both local and remote). Here are a few links to get you going in the right direction:
I hope these get you moving in the right direction! If you have read this, and aren’t sure what it all means, check out the Adobe Developer Connection to ramp up on HTML5, or theexpressiveweb.com to see what HTML5 & CSS3 can do.