This article needs a technical review. How you can help.
The touch interfaces enable applications to create enhanced user experiences on touch enabled devices. However, the reality is the vast majority of today's web content is designed only to work with mouse input. Consequently, even if a browser supports touch, the browser must still emulate mouse events so content that assumes mouse-only input will work as is without direct modification.
Ideally, a touch-based application does not need to explicitly address mouse input. However, because the browser must emulate mouse events, there may be some interaction issues that need to be handled. Below are some details about the interaction and the ramifications for application developers.
Event firing
The touch events standard defines a few browser requirements regarding touch and mouse interaction (see the Interaction with Mouse Events and click section for details), noting the browser may fire both touch events and mouse events in response to the same user input. This section describes the requirement that may affect an application.
If the browser fires both touch and mouse events because of a single user input, the browser must fire a touchstart before any mouse events. Consequently, if an application does not want mouse events fired on a specific touch target element, the element's touch event handlers should call preventDefault() and no additional mouse events will be dispatched.
Here is a code snippet of the touchmove event handler calling preventDefault().
// touchmove handler
function process_touchmove(ev) {
// Call preventDefault() to prevent any further handling
ev.preventDefault();
}
Event order
Although the specific ordering of touch and mouse events is implementation-defined, the standard indicates the following order is typical: for single input:
touchstart- Zero or more
touchmoveevents, depending on movement of the finger(s) touchendmousemovemousedownmouseupclick
If the touchstart, touchmove or touchend event is canceled during an interaction, no mouse or click events will be fired, and the resulting sequence of events would just be:
touchstart- Zero or more
touchmoveevents, depending on movement of the finger(s) touchend