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TouchEvent.touches - Web APIs 编辑

touches is a read-only TouchList listing all the Touch objects for touch points that are currently in contact with the touch surface, regardless of whether or not they've changed or what their target element was at touchstart time.

You can think of it as how many separate fingers are able to be identified as touching the screen.

Syntax

var touches = touchEvent.touches;

Return value

touches: A TouchList listing all the Touch objects for touch points that are still in contact with the touch surface, regardless of whether or not they've changed or what their target element was at touchstart time.

Example

This example illustrates the TouchEvent object's TouchEvent.touches property. The TouchEvent.touches property is a TouchList object and containing a list of Touch objects for every point of contact currently touching the surface.

In following code snippet, the touchstart event handler checks the length of the TouchEvent.touches list to determine the number of touch points that were activated and then invokes different handlers depending on the number of touch points.

someElement.addEventListener('touchstart', function(e) {
   // Invoke the appropriate handler depending on the
   // number of touch points.
   switch (e.touches.length) {
     case 1: handle_one_touch(e); break;
     case 2: handle_two_touches(e); break;
     case 3: handle_three_touches(e); break;
     default: console.log("Not supported"); break;
   }
 }, false);