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    TouchEvent

    A TouchEvent interface represents an event sent when the state of contacts with a touch-sensitive surface changes. This surface can be a touch screen or trackpad, for example. The event can describe one or more points of contact with the screen and includes support for detecting movement, addition and removal of contact points, and so forth.

    Touches are represented by the Touch object; each touch is described by a position, size and shape, amount of pressure, and target element. Lists of touches are represented by TouchList objects.

    Properties

    This interface inherits properties from its parent, UIEvent and Event.

    TouchEvent.altKey Read only
    A Boolean value indicating whether or not the alt key was down when the touch event was fired.
    TouchEvent.changedTouches Read only
    A TouchList of all the Touch objects representing individual points of contact whose states changed between the previous touch event and this one.
    TouchEvent.ctrlKey Read only
    A Boolean value indicating whether or not the control key was down when the touch event was fired.
    TouchEvent.metaKey Read only
    A Boolean value indicating whether or not the meta key was down when the touch event was fired.
    TouchEvent.shiftKey Read only
    A Boolean value indicating whether or not the shift key was down when the touch event was fired.
    TouchEvent.targetTouchesRead only
    A TouchList of all the Touch objects that are both currently in contact with the touch surface and were also started on the same element that is the target of the event.
    TouchEvent.touches Read only
    A TouchList of all the Touch objects representing all current points of contact with the surface, regardless of target or changed status.

    Methods

    This interface inherits methods from its parents UIEvent and Event.

    TouchEvent.initTouchEvent()
    Initializes a TouchEvent created via Document.createEvent("TouchEvent"). This method has no more effect once the event has been dispatched.

    Touch event types

    There are several types of event that can be fired to indicate that touch-related changes have occurred. You can determine which of these has happened by looking at the event's TouchEvent.type property.

    Note: It's important to note that in many cases, both touch and mouse events get sent (in order to let non-touch-specific code still interact with the user). If you use touch events, you should call event.preventDefault() to keep the mouse event from being sent as well.

    touchstart

    Sent when the user places a touch point on the touch surface. The event's target will be the element in which the touch occurred.

    touchend

    Sent when the user removes a touch point from the surface (that is, when they lift a finger or stylus from the surface). This is also sent if the touch point moves off the edge of the surface; for example, if the user's finger slides off the edge of the screen.

    The event's target is the same element that received the touchstart event corresponding to the touch point, even if the touch point has moved outside that element.

    The touch point (or points) that were removed from the surface can be found in the TouchList specified by the changedTouches attribute.

    touchmove

    Sent when the user moves a touch point along the surface. The event's target is the same element that received the touchstart event corresponding to the touch point, even if the touch point has moved outside that element.

    This event is also sent if the values of the radius, rotation angle, or force attributes of a touch point change.

    Note: The rate at which touchmove events is sent is browser-specific, and may also vary depending on the capability of the user's hardware. You must not rely on a specific granularity of these events.

    touchcancel

    Sent when a touch point has been disrupted in some way. There are several possible reasons why this might happen (and the exact reasons will vary from device to device, as well as browser to browser):

    • An event of some kind occurred that canceled the touch; this might happen if a modal alert pops up during the interaction.
    • The touch point has left the document window and moved into the browser's UI area, a plug-in, or other external content.
    • The user has placed more touch points on the screen than can be supported, in which case the earliest Touch in the TouchList gets canceled.

    Example

    See the example on the main Touch events article.

    See also



     

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    Contributors to this page: Sheppy, MHasan, fscholz, Pettay, acusti, kscarfone, bigbossSNK, teoli, wesj, Khannabyss
    Last updated by: fscholz,