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Amazon Silk
Developer Guide

Touch

As you might expect, Amazon Silk is designed for touch interactions and fully supports Touch Events. In general, Amazon Silk and other touch browsers know how to apply touch interactions to click-based DOM events, even with no mouse involved. For example, Silk will fire the following onclick event in response to a tap.

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<html> <body> <button onclick="testFunction()">Tap me</button> <div id="test"></div> <script> function testFunction() { document.getElementById("test").innerHTML="The tap fired an onclick event."; } </script> </body> </html>

In many web development scenarios, you can rely on this sort of compatability between mouse events and a touch interface. But touch gestures are more than just a substitute for mouse interactions. Touch is an integral part of the web browsing experience on a tablet, and if you want to go beyond parity with desktop functionality—that is, if you want to provide an experience tailored to a tablet or mobile form factor—providing added support for touch gestures is a good place to start.

Note

Designing for touch events can also provide a better experience for trackpad users.

The W3C makes several recommendations for touch-based interactions:

  • The spacing of selectable elements should be wide enough to accomodate direct selection.

  • The screen size of selectable elements should be sufficient to accomodate direct selection.

  • Because elements have to be selected to be in focus, you should be careful not to hide information behind a focus state.

The first two recommendations address the "fat finger" problem. If selectable page elements are small and densely placed, it's easy to select the wrong one. The solution is to design navigation elements that are large enough to be easily selected by touch.

The third item pertains to information that's intended to be hidden until an element comes into focus. The issue is that, with touch interactions, it can be problematic to distinguish between focusing on an element and selecting an element. This issue is particularly important when it comes to drop-down menus. On desktop, a user can trigger the :focus or :hover pseudoclasses by mousing over an element. Thus, for desktop you can create a drop-down navigation that displays child elements on mouseover. With a touch device, such hover menus are more complicated. To learn more about creating hover menus for Amazon Silk, see Create Drop-down Menus for a Touch Screen

Touch Example Using jQuery Mobile

Consider a few examples of DOM events specifically designed for touch. These examples use jQuery Mobile, as it provides good touch support. jQuery Mobile is a web development framework designed to make HTML5-compatible, responsive, touch-optimized websites. The example below specifies targets and create handlers for two touch events: tap and taphold.

Note

This example includes the jQuery libraries from a content delivery network, so you should be able to paste the code below directly into a page and run it without downloading any additional resources.

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<html> <head> <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=no"> <style> div.test { text-align: center; border-radius: .625em; background-color: #E6E6E6; padding: 1em; margin: .5em; } </style> <link rel="stylesheet" href="http://code.jquery.com/mobile/1.4.2/jquery.mobile-1.4.2.min.css" /> </head> <body> <div data-role="page" id="home"> <div data-role="header"> <h1>Welcome to Example Corp.</h1> <div data-role="navbar"> <ul> <li><a href="#home" class="ui-btn ui-btn-inline ui-corner-all">Home</a></li> <li><a href="#about" class="ui-btn ui-btn-inline ui-corner-all">About Us</a></li> <li><a href="#contact" class="ui-btn ui-btn-inline ui-corner-all">Contact</a></li> <li><a href="#news" class="ui-btn ui-btn-inline ui-corner-all">News</a></li> </ul> </div> </div> <div data-role="main" class="ui-content"> <div class="test tap">Tap</div> <div class="test taphold">Tap and hold</div> </div> <div data-role="footer"> <h1>&copy; 2013-2014 Example Corp.</h1> </div> </div> <script src="http://code.jquery.com/jquery-1.9.1.min.js"></script> <script src="http://code.jquery.com/mobile/1.4.2/jquery.mobile-1.4.2.min.js"></script> <script> $(function(){ $("div.test.tap").on("tap", function() { $(this).text("After tap event").css("background-color", "#86BDFF"); }); $("div.test.taphold").on("taphold", function() { $(this).text("After tap-and-hold event").css("background-color", "#FFBF4C"); }); }); </script> </body> </html>

Both the tap and taphold events are jQuery Mobile extensions of jQuery built-in methods. The tap event is fired by a quick touch event on an element. The taphold event is fired by a touch-and-hold event (that is, a long press) on an element. (By default, the jQuery Mobile taphold event is triggered by a sustained tap of 750 milliseconds, but you can change this.)

We could also have implemented other jQuery Mobile touch events, like swipe, swipeleft, and swiperight. The code above sets two anonymous callback functions, one on the div.test.tap selector, and one on the div.test.taphold selector. In each case, we're binding a target (div.test.tap or div.test.taphold) to an event (tap or taphold), and in each case the event handler modifies the CSS applied to the target element.

Here's what the page looks like immediately after page load:

And here's the page after the tap and tap-and-hold events.

The example above illustrates the beginning of a touch-friendly web design. Even in portrait mode, the top navigation links are wide enough to accommodate touch interactions comfortably. jQuery Mobile makes it especially easy to create such a touch-friendly design, and there are other options, too. Bootstrap is a design framework that provides good touch support, and there are various plugins available for improving touch support.

So here are the takeaways:

  • Design and develop with touch interactions in mind. Even if your site or application is not specifically targeted for touch devices, you should provide a good experience for all users.

  • Frameworks like jQuery Mobile and Bootstrap can help you provide a great experience to touch-device users. These frameworks won't be useful for every project, but creating touch-friendly interactions is important for every site.

Additional Resources