The features in this specification extend or modify those found in Pointer Events, a W3C Recommendation that describes events and related interfaces for handling hardware agnostic pointer input from devices including a mouse, pen, touchscreen, etc. For compatibility with existing mouse based content, this specification also describes a mapping to fire Mouse Events for other pointer device types.

This specification is an update to [[PointerEvents]] which was shipped broadly only by Microsoft Internet Explorer and Microsoft Edge (though a further independent and mostly interoperable implementation was present in a pre-release build of Mozilla Firefox when the Pointer Events specification was published as a W3C Recommendation). Level 2 includes editorial clarifications, new features and minor breaking changes that address certain limitations and concerns that have been raised about aspects of the design, in an effort to enable wider browser adoption.

Introduction

Today, most [[HTML5]] content is used with and/or designed for mouse input. Those that handle input in a custom manner typically code to [[!DOM-LEVEL-3-EVENTS]] Mouse Events. Newer computing devices today, however, incorporate other forms of input, including touchscreens, pen input, etc. Event types have been proposed for handling each of these forms of input individually. However, that approach often incurs unnecessary duplication of logic and event handling overhead when adding support for a new input type. This often creates a compatibility problem when content is written with only one device type in mind. Additionally, for compatibility with existing mouse-based content, most user agents fire Mouse Events for all input types. This makes it ambiguous whether a Mouse Event represents an actual mouse device or is being produced from another input type for compatibility, which makes it hard to code to both device types simultaneously.

To reduce the cost of coding to multiple input types and also to help with the above described ambiguity with Mouse Events, this specifications defines a more abstract form of input, called a pointer. A pointer can be any point of contact on the screen made by a mouse cursor, pen, touch (including multi-touch), or other pointing input device. This model makes it easier to write sites and applications that work well no matter what hardware the user has. For scenarios when device-specific handling is desired, this specification also defines properties for inspecting the device type which produced the event. The primary goal is to provide a single set of events and interfaces that allow for easier authoring for cross-device pointer input while still allowing for device-specific handling only when necessary for an augmented experience.

An additional key goal is to enable multi-threaded user agents to handle default touch actions, such as scrolling, without blocking on script execution.

While this specification defines a unified event model for a variety of pointer inputs, this model does not cover other forms of input such as keyboards or keyboard-like interfaces (for instance, a screenreader or similar assistive technology running on a touchscreen-only device, which allows users sequential navigation through focusable controls and elements). While user agents might choose to also generate pointer events in response to these interfaces, this scenario is not covered in this specification.

In the first instance, authors are encouraged to provide equivalent functionality for all forms of input by responding to high-level events such as focus, blur and click. However, when using low-level events (such as Pointer Events), authors are encouraged to ensure that all types of input are supported. In the case of keyboards and keyboard-like interfaces, this might require the addition of explicit keyboard event handling. See WCAG 2.0 Guideline 2.1 for further details.

Pointer input combines input from mouse, pen, touch, etc.
A pointer is a hardware agnostic representation of input devices that can target a specific coordinate (or set of coordinates) on a screen.

The events for handling generic pointer input look a lot like those for mouse: pointerdown, pointermove, pointerup, pointerover, pointerout, etc. This facilitates easy content migration from Mouse Events to Pointer Events. Pointer Events provide all the usual properties present in Mouse Events (client coordinates, target element, button states, etc.) in addition to new properties for other forms of input: pressure, contact geometry, tilt, etc. So authors can easily code to Pointer Events to share logic between different input types where it makes sense, and customize for a particular type of input only where necessary to get the best experience.

While Pointer Events are sourced from a variety of input devices, they are not defined as being generated from some other set of device-specific events. While possible and encouraged for compatibility, this spec does not require other device-specific events be supported (e.g. mouse events, touch events, etc.). A user agent could support pointer events without supporting any other device events. For compatibility with content written to mouse-specific events, this specification does provide an optional section describing how to generate compatibility mouse events based on pointer input from devices other than a mouse.

This specification does not provide any advice on the expected behavior of user agents that support both Touch Events (as defined in [[TOUCH-EVENTS]]) and Pointer Events. For more information on the relationship between these two specifications, see the Touch Events Community Group.

Examples

The following are example author code that demonstrates how the APIs in this specification might be used.

/* Bind to either Pointer Events or traditional touch/mouse */

if (window.PointerEvent) {
    // if Pointer Events are supported, only listen to pointer events
    target.addEventListener("pointerdown", function(e) {
        // if necessary, apply separate logic based on e.pointerType
        // for different touch/pen/mouse behavior
        ...
    });
    ...
} else {
    // traditional touch/mouse event handlers
    target.addEventListener('touchstart', function(e) {
        // prevent compatibility mouse events and click
        e.preventDefault();
        ...
    });
    ...
    target.addEventListener('mousedown', ...);
    ...
}

// additional event listeners for keyboard handling
...
window.addEventListener("pointerdown", detectInputType);

function detectInputType(event) {
    switch(event.pointerType) {
        case "mouse":
            /* mouse input detected */
            break;
        case "pen":
            /* pen/stylus input detected */
            break;
        case "touch":
            /* touch input detected */
            break;    
        default:
            /* pointerType is empty (could not be detected) 
            or UA-specific custom type */
    }
}
<style>
  /* Disable intrinsic user agent touch behaviors (such as panning or zooming) so 
  that all events on the canvas element are given to the application instead. */
  
  canvas { touch-action: none; }
</style>

<canvas id="drawSurface" width="500px" height="500px" style="border:1px solid black;"></canvas>

<script>
    var canvas = document.getElementById("drawSurface"),
    context = canvas.getContext("2d");

    if (window.PointerEvent) {
        canvas.addEventListener("pointermove", paint);
        if(window.navigator.maxTouchPoints>1)
           // user agent and hardware support multi-touch
           ...
    } else {
        // provide fallback for user agents that do not support Pointer Events
        canvas.addEventListener("mousemove", paint);
    }

    function paint(event) {
        if(event.buttons>0)
           context.fillRect(event.clientX, event.clientY, 5, 5);
    }

    // additional event listeners/functions for keyboard handling
    ...
</script>
<div style="position:absolute; top:0px; left:0px; width:100px;height:100px;"></div>
<script>
window.addEventListener("pointerdown", checkPointerSize);

function checkPointerSize(event) {
    event.target.style.width = event.width + "px";
    event.target.style.height = event.height + "px";
}
</script>
var event = new PointerEvent("pointerover",
  { bubbles: true, 
    cancelable: true, 
    composed: true,
    pointerId: 42,
    pointerType: "pen",
    clientX: 300,
    clientY: 500
  });
eventTarget.dispatchEvent(event);

Glossary

active buttons state
The condition when a pointer has a non-zero value for the buttons property. For mouse, this is when the device has at least one button depressed. For touch, this is when there is physical contact with the digitizer. For pen, this is when either the pen has physical contact with the digitizer, or at least one button is depressed while hovering.
active pointer
Any touch contact, pen stylus, mouse cursor, or other pointer that can produce events. If it is possible for a given pointer (identified by a unique pointerId) to produce additional events within the document, then that pointer is still considered active. Examples:
  • A mouse connected to the device is always active.
  • A touch contact on the screen is considered active.
  • If a touch contact or pen stylus is lifted beyond the range of the digitizer, then it is no longer considered active.
On some platforms, the set of active pointers includes all pointer input to the device, including any that are not targeted at the user agent (e.g. those targeted at other applications).
Each active pointer should have the same id within the scope of the top-level browsing context (as defined by [[!HTML5]]). However, there is no such guarantee across multiple top-level browsing contexts.
canceled event
An event whose default action was prevented by means of preventDefault(), returning false in an event handler, or other means as defined by [[!DOM-LEVEL-3-EVENTS]] and [[!HTML5]].
contact geometry
The bounding box of an input (most commonly, touch) on a digitizer. This typically refers to devices with coarser pointer input resolution than a single pixel. Some devices do not report this data at all.
digitizer
A type of input sensing device in which a surface can detect input which is in contact and/or in close proximity. Most commonly, this is the surface that senses input from the touch contact or a pen stylus.
hit test
The process by which a user agent determines a target element for a pointer event. Typically, this is determined by considering the pointer's location and also the visual layout of elements in a document on screen media.
pointer
A hardware agnostic representation of input devices that can target a specific coordinate (or set of coordinates) on a screen, such as a mouse, pen, or touch contact.
user agent
A program, such as a browser or content authoring tool, normally running on a client machine, which acts on a user's behalf in retrieving, interpreting, executing, presenting, or creating content.
queue a task
Adding the task to events task queue of the relevant event loop, as defined in [[!HTML5]].

Pointer Events and Interfaces

PointerEvent Interface

dictionary PointerEventInit : MouseEventInit {
    long        pointerId = 0;
    double      width = 1;
    double      height = 1;
    float       pressure = 0;
    float       tangentialPressure = 0;
    long        tiltX = 0;
    long        tiltY = 0;
    long        twist = 0;
    DOMString   pointerType = "";
    boolean     isPrimary = false;
};

[Constructor(DOMString type, optional PointerEventInit eventInitDict)]
interface PointerEvent : MouseEvent {
    readonly        attribute long        pointerId;
    readonly        attribute double      width;
    readonly        attribute double      height;
    readonly        attribute float       pressure;
    readonly        attribute float       tangentialPressure;
    readonly        attribute long        tiltX;
    readonly        attribute long        tiltY;
    readonly        attribute long        twist;
    readonly        attribute DOMString   pointerType;
    readonly        attribute boolean     isPrimary;
};
              
pointerId

A unique identifier for the pointer causing the event. This identifier MUST be unique from all other active pointers in the top-level browsing context (as defined by [[!HTML5]]) at the time. A user agent MAY recycle previously retired values for pointerId from previous active pointers, if necessary.

The pointerId selection algorithm is implementation specific. Therefore authors cannot assume values convey any particular meaning other than an identifier for the pointer that is unique from all other active pointers. As an example, values are not guaranteed to be monotonically increasing.
width

The width (magnitude on the X axis), in CSS pixels (see [[CSS21]]), of the contact geometry of the pointer. This value MAY be updated on each event for a given pointer. For inputs that typically lack contact geometry (such as a traditional mouse), and in cases where the actual geometry of the input is not detected by the hardware, the user agent MUST return a default value of 1.

height

The height (magnitude on the Y axis), in CSS pixels (see [[CSS21]]), of the contact geometry of the pointer. This value MAY be updated on each event for a given pointer. For inputs that typically lack contact geometry (such as a traditional mouse), and in cases where the actual geometry of the input is not detected by the hardware, the user agent MUST return a default value of 1.

pressure

The normalized pressure of the pointer input in the range of [0,1], where 0 and 1 represent the minimum and maximum pressure the hardware is capable of detecting, respectively. For hardware that does not support pressure, the value MUST be 0.5 when in the active buttons state and 0 otherwise. Note: all pointerup events will have pressure 0.

tangentialPressure

The normalized tangential pressure (also known as barrel pressure), typically set by an additional control (e.g. a finger wheel on an airbrush stylus), of the pointer input in the range of [-1,1], where 0 is the neutral position of the control. Note that some hardware may only support positive values in the range of [0,1]. For hardware that does not support tangential pressure, the value MUST be 0.

tiltX

The plane angle (in degrees, in the range of [-90,90]) between the Y-Z plane and the plane containing both the transducer (e.g. pen stylus) axis and the Y axis. A positive tiltX is to the right. tiltX can be used along with tiltY to represent the tilt away from the normal of a transducer with the digitizer. For devices that do not report tilt, the value MUST be 0.

tiltX explanation diagram
Positive tiltX.
tiltY

The plane angle (in degrees, in the range of [-90,90]) between the X-Z plane and the plane containing both the transducer (e.g. pen stylus) axis and the X axis. A positive tiltY is towards the user. tiltY can be used along with tiltX to represent the tilt away from the normal of a transducer with the digitizer. For devices that do not report tilt, the value MUST be 0.

tiltY explanation diagram
Negative tiltY.
twist

The clockwise rotation (in degrees, in the range of [0,359]) of a transducer (e.g. pen stylus) around its own major axis. For devices that do not report twist, the value MUST be 0.

pointerType

Indicates the device type that caused the event (mouse, pen, touch, etc.). If a user agent is to fire a pointer event for a mouse, pen stylus, or touch input device, then the value of pointerType MUST be according to the following table:

Pointer Device TypepointerType Value
Mousemouse
Pen Styluspen
Touch Contacttouch

If the device type cannot be detected by the user agent, then the value MUST be an empty string. If a user agent supports pointer device types other than those listed above, the value of pointerType SHOULD be vendor prefixed to avoid conflicting names for different types of devices. Future specifications MAY provide additional normative values for other device types.

See Example 2 for a basic demonstration of how the pointerType can be used. Also note that developers should include some form of default handling to cover user agents that may have implemented their own custom pointerType values and for situations where pointerType is simply an empty string.
isPrimary

Indicates if the pointer represents the primary pointer of this pointer type.

The PointerEventInit dictionary is used by the PointerEvent interface's constructor to provide a mechanism by which to construct untrusted (synthetic) pointer events. It inherits from the MouseEventInit dictionary defined in [[!DOM-LEVEL-3-EVENTS]]. The steps for constructing an event are defined in [[!DOM4]]. See the examples for sample code demonstrating how to fire an untrusted pointer event.

The PointerEvent interface inherits from MouseEvent, defined in [[DOM-LEVEL-3-EVENTS]] and extended by [[CSSOM-VIEW]].

Button States

Chorded Button Interactions

Some pointer devices, such as mouse or pen, support multiple buttons. In the [[!DOM-LEVEL-3-EVENTS]] Mouse Event model, each button press produces a mousedown and mouseup event. To better abstract this hardware difference and simplify cross-device input authoring, Pointer Events do not fire overlapping pointerdown and pointerup events for chorded button presses (depressing an additional button while another button on the pointer device is already depressed).

Instead, chorded button presses can be detected by inspecting changes to the button and buttons properties. The button and buttons properties are inherited from the [[!DOM-LEVEL-3-EVENTS]] MouseEvent interface, but with a change in semantics and values, as outlined in the following sections.

The modifications to the button and buttons properties apply only to pointer events. For any compatibility mouse events the value of button and buttons should follow [[!DOM-LEVEL-3-EVENTS]].

The button property

To identify button state transitions in any pointer event (and not just pointerdown and pointerup), the button property indicates the device button whose state-change fired the event.

Device Button Changesbutton
Neither buttons nor touch/pen contact changed since last event-1
Left Mouse,
Touch Contact,
Pen contact
0
Middle Mouse1
Right Mouse,
Pen barrel button
2
X1 (back) Mouse3
X2 (forward) Mouse4
Pen eraser button5
During a mouse drag, the value of the button property in a pointermove event will be different from that in a mousemove event. For example, while moving the mouse with the right button pressed, the pointermove events will have the button value -1, but the mousemove events will have the button value 2.

The buttons property

The buttons property gives the current state of the device buttons as a bitmask (same as in MouseEvent, but with an expanded set of possible values).

Current state of device buttonsbuttons
Mouse moved with no buttons pressed,
Pen moved while hovering with no buttons pressed
0
Left Mouse,
Touch Contact,
Pen contact
1
Middle Mouse4
Right Mouse,
Pen barrel button
2
X1 (back) Mouse8
X2 (forward) Mouse16
Pen eraser button32

The Primary Pointer

In a multi-pointer (e.g. multi-touch) scenario, the isPrimary property is used to identify a master pointer amongst the set of active pointers for each pointer type.

  • At any given time, there can only ever be at most one primary pointer for each pointer type.
  • The first pointer to become active for a particular pointer type (e.g. the first finger to touch the screen in a multi-touch interaction) becomes the primary pointer for that pointer type.
  • Only a primary pointer will produce compatibility mouse events. In the case where there are multiple primary pointers, these pointers will all produce compatibility mouse events.
Authors who desire single-pointer interaction can achieve this by ignoring non-primary pointers (however, see the note below on multiple primary pointers).
When two or more pointer device types are being used concurrently, multiple pointers (one for each pointerType) are considered primary. For example, a touch contact and a mouse cursor moved simultaneously will produce pointers that are both considered primary.
In some cases, it is possible for the user agent to fire pointer events in which no pointer is marked as a primary pointer. For instance, when there are multiple active pointers of a particular type like multi-touch and the primary pointer is removed (e.g. it leaves the screen), there will be no primary pointer events. Also on the platforms where the primary pointer is determined using all active pointers on the device (including those targeted at an application other than the user agent), if the first touch interaction is targeted outside the user agent and a secondary (multi-touch) touch interaction is targeted inside the user agent, then the user agent may fire pointer events for the second contact with a value of false for isPrimary.
Current operating systems and user agents don't usually have a concept of multiple mouse inputs. When more than one mouse device is present (for instance, on a laptop with both a trackpad and an external mouse), all mouse devices are generally treated as a single device - movements on any of the devices are translated to movement of a single mouse pointer, and there is no distinction between button presses on different mouse devices. For this reason, there will usually only be a single mouse pointer, and that pointer will be primary.

Firing events using the PointerEvent interface

To fire a pointer event named e means to fire an event named e as defined in [[!DOM4]] with an event using the PointerEvent interface whose attributes are set as defined in PointerEvent Interface, and Pointer Event types.

If the event is not gotpointercapture or lostpointercapture, run Process Pending Pointer Capture steps for this PointerEvent.

The target object at which the event is fired is determined as follows:

If this is a pointerdown event, the associated device is a direct manipulation device and the target is an Element, then set pointer capture for this pointerId to the target element as described in implicit pointer capture.

Fire the event to the determined target.

Using the pointer capture target override as the target instead of the normal hit-test result may fire some boundary events. This is the same as the pointer leaving its previous target and entering this new capturing target and if they are different targets boundary events should be dispatched first. When the capture is released the same scenario may happen as the pointer is leaving the capturing target and entering the hit-test target.

Process Pending Pointer Capture

The user agent MUST run the following steps when implicitly releasing pointer capture as well as when firing Pointer Events that are not gotpointercapture or lostpointercapture.

  1. If the pointer capture target override for this pointer is set and is not equal to the pending pointer capture target override, then fire a pointer event named lostpointercapture at the pointer capture target override node.
  2. If the pending pointer capture target override for this pointer is set and is not equal to the pointer capture target override, then fire a pointer event named gotpointercapture at the pending pointer capture target override.
  3. Set the pointer capture target override to the pending pointer capture target override, if set. Otherwise, clear the pointer capture target override.

Pointer Event types

The following table provides a summary of the event types defined in this specification.

Event TypeSync/AsyncBubblesCancelableDefault Action
pointerover Sync Yes Yes None
pointerenter Sync No No None
pointerdown Sync Yes Yes Varies: when the pointer is primary, all default actions of the mousedown event
Canceling this event also sets the PREVENT MOUSE EVENT flag for this pointerType, which prevents subsequent firing of certain compatibility mouse events.
pointermove Sync Yes Yes Varies: when the pointer is primary, all default actions of mousemove
pointerup Sync Yes Yes Varies: when the pointer is primary, all default actions of mouseup
pointercancel Sync Yes No None
pointerout Sync Yes Yes None
pointerleave Sync No No None
gotpointercapture Sync/Async Yes No None
lostpointercapture Sync/Async Yes No None

For all pointer events in the table above, composed ([[!WHATWG-DOM]]) attribute SHOULD be true and detail [[!DOM-LEVEL-3-EVENTS]] attribute SHOULD be 0.

For gotpointercapture and lostpointercapture all the attributes except the ones defined in the table above should be the same as the Pointer Event that caused the user agent to run Process Pending Pointer Capture and fire the gotpointercapture and lostpointercapture events.

In the case of the primary pointer, these events (with the exception of gotpointercapture and lostpointercapture) may also fire compatibility mouse events.

The pointerover event

A user agent MUST fire a pointer event named pointerover when a pointing device is moved into the hit test boundaries of an element. Note that setPointerCapture or releasePointerCapture might have changed the hit test target. A user agent MUST also fire this event prior to firing a pointerdown event for devices that do not support hover (see pointerdown).

The pointerenter event

A user agent MUST fire a pointer event named pointerenter when a pointing device is moved into the hit test boundaries of an element or one of its descendants, including as a result of a pointerdown event from a device that does not support hover (see pointerdown). Note that setPointerCapture or releasePointerCapture might have changed the hit test target. This event type is similar to pointerover, but differs in that it does not bubble.

There are similarities between this event type, the mouseenter event described in [[DOM-LEVEL-3-EVENTS]], and the CSS :hover pseudo-class described in [[CSS21]]. See also the pointerleave event.

The pointerdown event

A user agent MUST fire a pointer event named pointerdown when a pointer enters the active buttons state. For mouse, this is when the device transitions from no buttons depressed to at least one button depressed. For touch, this is when physical contact is made with the digitizer. For pen, this is when the pen either makes physical contact with the digitizer without any button depressed, or transitions from no buttons depressed to at least one button depressed while hovering.

For mouse (or other multi-button pointer devices), this means pointerdown and pointerup are not fired for all of the same circumstances as mousedown and mouseup. See chorded buttons for more information.

For input devices that do not support hover, a user agent MUST also fire a pointer event named pointerover followed by a pointer event named pointerenter prior to dispatching the pointerdown event.

Authors can prevent the firing of certain compatibility mouse events by canceling the pointerdown event (if the isPrimary property is true). This sets the PREVENT MOUSE EVENT FLAG on the pointer. Note, however, that this does not prevent the mouseover, mouseenter, mouseout, or mouseleave events from firing.

The pointermove event

A user agent MUST fire a pointer event named pointermove when a pointer changes coordinates. Additionally, when a pointer changes button state, pressure, tangential pressure, tilt, twist, or contact geometry (e.g. width and height) and the circumstances produce no other pointer events defined in this specification then a user agent MUST fire a pointer event named pointermove.

The pointerup event

A user agent MUST fire a pointer event named pointerup when a pointer leaves the active buttons state. For mouse, this is when the device transitions from at least one button depressed to no buttons depressed. For touch, this is when physical contact is removed from the digitizer. For pen, this is when the pen is removed from the physical contact with the digitizer while no button is depressed, or transitions from at least one button depressed to no buttons depressed while hovering.

For input devices that do not support hover, a user agent MUST also fire a pointer event named pointerout followed by a pointer event named pointerleave after dispatching the pointerup event.

For mouse (or other multi-button pointer devices), this means pointerdown and pointerup are not fired for all of the same circumstances as mousedown and mouseup. See chorded buttons for more information.

The pointercancel event

A user agent MUST fire a pointer event named pointercancel in the following circumstances:

  • The user agent has determined that a pointer is unlikely to continue to produce events (for example, because of a hardware event).
  • After having fired the pointerdown event, if the pointer is subsequently used to manipulate the page viewport (e.g. panning or zooming).

After firing the pointercancel event, a user agent MUST also fire a pointer event named pointerout followed by firing a pointer event named pointerleave.

This section is non-normative.

Examples of scenarios in which a user agent might determine that a pointer is unlikely to continue to produce events include:

  • A device's screen orientation is changed while a pointer is active.
  • The user inputs a greater number of simultaneous pointers than is supported by the device.
  • The user agent interprets the input as accidental (for example, the hardware supports palm rejection).

Methods for changing the device's screen orientation, recognizing accidental input, or using a pointer to manipulate the viewport (e.g. panning or zooming) are out of scope for this specification.

The pointerout event

A user agent MUST fire a pointer event named pointerout when any of the following occurs:

  • A pointing device is moved out of the hit test boundaries of an element. Note that setPointerCapture or releasePointerCapture might have changed the hit test target.
  • After firing the pointerup event for a device that does not support hover (see pointerup).
  • After firing the pointercancel event (see pointercancel).
  • When a pen stylus leaves the hover range detectable by the digitizer.

The pointerleave event

A user agent MUST fire a pointer event named pointerleave when a pointing device is moved out of the hit test boundaries of an element and all of its descendants, including as a result of a pointerup and pointercancel events from a device that does not support hover (see pointerup and pointercancel). Note that setPointerCapture or releasePointerCapture might have changed the hit test target. User agents MUST also fire a pointer event named pointerleave when a pen stylus leaves hover range detectable by the digitizer. This event type is similar to pointerout, but differs in that it does not bubble and that it MUST not be fired until the pointing device has left the boundaries of the element and the boundaries of all of its descendants.

There are similarities between this event type, the mouseleave event described in [[DOM-LEVEL-3-EVENTS]], and the CSS :hover pseudo-class described in [[CSS21]]. See also the pointerenter event.

The gotpointercapture event

A user agent MUST fire a pointer event named gotpointercapture when an element receives pointer capture. This event is fired at the element that is receiving pointer capture. Subsequent events for that pointer will be fired at this element. See the Setting Pointer Capture and Process Pending Pointer Capture sections.

The lostpointercapture event

A user agent MUST fire a pointer event named lostpointercapture after pointer capture is released for a pointer. This event MUST be fired prior to any subsequent events for the pointer after capture was released. This event is fired at the element from which pointer capture was removed. Subsequent events for the pointer follow normal hit testing mechanisms (out of scope for this specification) for determining the event target. See the Releasing Pointer Capture, Implicit Release of Pointer Capture, and Process Pending Pointer Capture sections.

Extensions to the Element interface

The following section describes extensions to the existing Element interface, defined in [[!HTML5]], to facilitate the setting and releasing of pointer capture.

partial interface Element {
  attribute EventHandler ongotpointercapture;
  attribute EventHandler onlostpointercapture;
  void setPointerCapture (long pointerId);
  void releasePointerCapture (long pointerId);
  boolean hasPointerCapture (long pointerId);
};
            
ongotpointercapture
The event handler IDL attribute (see [[!HTML5]]) for the gotpointercapture event type.
onlostpointercapture
The event handler IDL attribute (see [[!HTML5]]) for the lostpointercapture event type.
setPointerCapture

Sets pointer capture for the pointer identified by the argument pointerId to the element on which this method is invoked. For subsequent events of the pointer, the capturing target will substitute the normal hit testing result as if the pointer is always over the capturing target, and they MUST always be targeted at this element until capture is released. The pointer MUST be in its active buttons state for this method to be effective, otherwise it fails silently. Throws a DOMException with the name InvalidPointerId when the provided method's argument does not match any of the active pointers.

releasePointerCapture

Releases pointer capture for the pointer identified by the argument pointerId from the element on which this method is invoked. Subsequent events for the pointer follow normal hit testing mechanisms (out of scope for this specification) for determining the event target. Throws a DOMException with the name InvalidPointerId when the provided the method's argument does not match any of the active pointers.

hasPointerCapture

Indicates whether the element on which this method is invoked has pointer capture for the pointer identified by the argument pointerId. In particular, returns true if the pending pointer capture target override for pointerId is set to the element on which this method is invoked, and false otherwise.

This method will return true immediately after a call to setPointerCapture, even though that element will not yet have received a gotpointercapture event. As a result it can be useful for detecting implicit pointer capture from inside of a pointerdown event listener.

Extensions to the GlobalEventHandlers interface

The following section describes extensions to the existing GlobalEventHandlers interface, defined in [[!HTML5]], to facilitate the event handler registration.

partial interface GlobalEventHandlers {
    attribute EventHandler onpointerdown;
    attribute EventHandler onpointermove;
    attribute EventHandler onpointerup;
    attribute EventHandler onpointercancel;
    attribute EventHandler onpointerover;
    attribute EventHandler onpointerout;
    attribute EventHandler onpointerenter;
    attribute EventHandler onpointerleave;
};
            
onpointerdown
The event handler IDL attribute (see [[!HTML5]]) for the pointerdown event type.
onpointermove
The event handler IDL attribute (see [[!HTML5]]) for the pointermove event type.
onpointerup
The event handler IDL attribute (see [[!HTML5]]) for the pointerup event type.
onpointercancel
The event handler IDL attribute (see [[!HTML5]]) for the pointercancel event type.
onpointerover
The event handler IDL attribute (see [[!HTML5]]) for the pointerover event type.
onpointerout
The event handler IDL attribute (see [[!HTML5]]) for the pointerout event type.
onpointerenter
The event handler IDL attribute (see [[!HTML5]]) for the pointerenter event type.
onpointerleave
The event handler IDL attribute (see [[!HTML5]]) for the pointerleave event type.

Extensions to the Navigator interface

The Navigator interface is defined in [[!HTML5]]. This specification extends the Navigator interface to provide device detection support.

partial interface Navigator {
    readonly  attribute long maxTouchPoints;
};
            
maxTouchPoints

The maximum number of simultaneous touch contacts supported by the device. In the case of devices with multiple digitizers (e.g. multiple touchscreens), the value MUST be the maximum of the set of maximum supported contacts by each individual digitizer.

For example, suppose a device has 3 touchscreens, which support 2, 5, and 10 simultaneous touch contacts, respectively. The value of maxTouchPoints should be 10.

While a maxTouchPoints value of greater than 0 indicates the user's device is capable of supporting touch input, it does not necessarily mean the user will use touch input. Authors should be careful to also consider other input modalities that could be present on the system, such as mouse, pen, screen readers, etc.
maxTouchPoints is often used to ensure that the interaction model of the content can be recognized by the current hardware. UI affordances can be provided to users with less capable hardware. On platforms where the precise number of touch points is not known, the minimum number guaranteed to be recognized is provided. Therefore, it is possible for the number of recognized touch points to exceed the value of maxTouchPoints.

Declaring candidate regions for default touch behaviors

For touch input, the default action of any and all pointer events MUST NOT be a manipulation of the viewport (e.g. panning or zooming).

Touch manipulations are intentionally not a default action of pointer events. Removing this dependency on the cancellation of events facilitates performance optimizations by the user agent.

The touch-action CSS property

Name:touch-action
Value:auto | none | [ [ pan-x | pan-left | pan-right ] || [ pan-y | pan-up | pan-down ] ] | manipulation
Initial:auto
Applies to:all elements except: non-replaced inline elements, table rows, row groups, table columns, and column groups.
Inherited:no
Percentages:N/A
Media:visual
Computed value:Same as specified value.

The touch-action CSS property determines whether touch input MAY trigger default behavior supplied by user agent. This includes, but is not limited to, behaviors such as panning or zooming.

When a user touches an element, the effect of that touch is determined by the value of the touch-action property and the default touch behaviors on the element and its ancestors. A touch behavior is supported if allowed by the touch-action properties of all elements between the hit tested element and it's nearest ancestor with the default touch behavior (including both the hit tested element and the element with the default touch behavior).

Some user agents support touch actions triggered by interactions of multiple concurrent pointers (e.g. multi-touch). Methods for processing or associating the touch-action values of multiple concurrent pointers is out of scope for this specification.

During the execution of a user agent touch behavior, the user agent MUST NOT fire subsequent pointer events for the pointer. The user agent MUST fire a pointer event named pointercancel (and subsequently a pointerout event and one or more pointerleave events) whenever all of the following are true, in order to end the stream of events for the pointer:

Once a touch action has been started, and the user agent has already determined whether or not the action should be handled as a user agent touch behavior, any changes to the relevant touch-action value will be ignored for the duration of the touch action. For instance, programmatically changing the touch-action value for an element from auto to none as part of a pointerdown handler script will not result in the user agent aborting or suppressing any default touch behavior for that touch for as long as that pointer is active.

Values have the following meanings:

auto
The user agent MAY determine any permitted touch behaviors, such as panning and zooming manipulations of the viewport, for touches that begin on the element.
none
Touches that begin on the element MUST NOT trigger default touch behaviors.
pan-x
pan-left
pan-right
pan-y
pan-up
pan-down

The user agent MAY consider touches that begin on the element only for the purposes of scrolling that starts in any of the directions specified by all of the listed values. Once scrolling is started, the direction may be reversed by the user even if scrolls that start in the reversed direction are disallowed. In contrast, when scrolling is restricted to starting along a single axis (eg. pan-y), the axis cannot be changed during the scroll.

In the case of pan-left, pan-right, pan-up and pan-down, the direction is interpreted as the opposite of the physical movement in the screen co-ordinate space. For example, pan-up always corresponds to input event sequences where typically (ignoring situations such as iframe containers with CSS rotation transforms) screenY is increasing (i.e. an interaction where the user moves a touch point down the screen).

manipulation
The user agent MAY consider touches that begin on the element only for the purposes of scrolling and continuous zooming. Any additional behaviors supported by auto are out of scope for this specification.
The terms "pan" and "scroll" are considered synonymous. Defining an interaction or gesture for triggering panning or scrolling, or for triggering behavior for the auto or none values are out of scope for this specification.
The touch-action property only applies to elements that support both the CSS width and height properties (see [[CSS21]]). This restriction is designed to facilitate user agent optimizations for low-latency touch actions. For elements not supported by default, such as <span> which is a non-replaced inline element (see [[HTML5]]), authors can set the display CSS property to a value, such as block, that supports width and height. Future specifications could extend this API to all elements.

The direction-specific pan values are useful for customizing overscroll behavior. For example, to implement a simple pull-to-refresh effect the document's touch-action can be set to pan-x pan-down whenever the scroll position is 0 and pan-x pan-y otherwise. This allows pointer event handlers to define the behavior for upward scrolls that start from the top of the document.

The direction-specific pan values can also be used for composing a component that implements custom panning with pointer event handling within an element that scrolls natively (or vice-versa). For example, an image carousel may use pan-y to ensure it receives pointer events for any horizontal pan operations without interfering with vertical scrolling of the document. When the carousel reaches its right-most extent, it may change its touch-action to pan-y pan-right so that a subsequent pan operation beyond it's extent can scroll the document within the viewport if possible. It's not possible to change the behavior of a pan in the middle of an operation.

Disabling some default touch behaviors may allow user agents to respond to other behaviors more quickly. For example, with auto user agents typically add 300ms of delay before click to allow for double-tap gestures to be handled. In these cases, explicitly setting touch-action: none or touch-action: manipulation will remove this delay. Note that the methods for determining a tap or double-tap gesture are out of scope for this specification.
<div style="touch-action: none;">
    This element receives pointer events for all touches.
</div>
<div style="touch-action: pan-x;">
    This element receives pointer events when not panning in the horizontal direction.
</div>
<div style="overflow: auto;">
    <div style="touch-action: none;">
        This element receives pointer events for all touches.
    </div>
    <div>
        Touches on this element MAY be consumed for manipulating the parent.
    </div>
</div>    
<div style="overflow: auto;">
    <div style="touch-action: pan-y;">
        <div style="touch-action: pan-x;">
            This element receives pointer events for all touches because
            it allows only horizontal panning yet an intermediate ancestor 
            (between it and the pannable element) only allows vertical panning. 
            Therefore, no touch behaviors are allowed.
        </div>
    </div>
</div>    
<div style="overflow: auto;">
    <div style="touch-action: pan-y pan-left;">
        <div style="touch-action: pan-x;">
            This element receives pointer events when not panning to the left.
        </div>
    </div>
</div>   

Pointer Capture

Pointer capture allows the events for a particular pointer (including any compatibility mouse events) to be retargeted to a particular element other than the normal hit test result of the pointer's location. This is useful in scenarios like a custom slider control (e.g. similar to the [[HTML5]] <input type="range"> control). Pointer capture can be set on the slider thumb element, allowing the user to slide the control back and forth even if the pointer slides off of the thumb.

Custom Volume Slider
Example of a custom slider control that chooses a value by sliding the thumb element back and forth. After pointerdown on the thumb, pointer capture can be used to allow the user to slide the thumb even if the pointer drifts off of it.

Setting Pointer Capture

Pointer capture is set on an element by calling the element.setPointerCapture(pointerId) method. When this method is invoked, a user agent MUST run the following steps:

  1. If the pointerId provided as the method's argument does not match any of the active pointers, then throw a DOMException with the name InvalidPointerId.
  2. If the Element on which this method is invoked does not participate in its ownerDocument's tree, throw an exception with the name InvalidStateError.
  3. If the pointer is not in the active buttons state, then terminate these steps.
  4. For the specified pointerId, set the pending pointer capture target override to the Element on which this method was invoked.

Releasing Pointer Capture

Pointer capture is released on an element explicitly by calling the element.releasePointerCapture(pointerId) method. When this method is called, a user agent MUST run the following steps:

  1. If the pointerId provided as the method's argument does not match any of the active pointers and these steps are not being invoked as a result of the implicit release of pointer capture, then throw a DOMException with the name InvalidPointerId.
  2. If hasPointerCapture is false for the Element with the specified pointerId, then terminate these steps.
  3. For the specified pointerId, clear the pending pointer capture target override, if set.

Implicit Pointer Capture

Some input devices (such as touchscreens) implement a "direct manipulation" metaphor where a pointer is intended to act primarily on the UI element it became active upon (providing a physical illusion of direct contact, instead of indirect contact via a cursor that conceptually floats above the UI). Such devices are identified by the InputDeviceCapabilities.pointerMovementScrolls property and should have "implicit pointer capture" behavior as follows.

Direct manipulation devices should behave exactly as if setPointerCapture was called on the target element just before the invocation of any pointerdown listeners. The hasPointerCapture API may be used (eg. within any pointerdown listener) to determine whether this has occurred. If releasePointerCapture is not called for the pointer before the next pointer event is fired, then a gotpointercapture event will be dispatched to the target (as normal) indicating that capture is active.

This is a breaking change from [[PointerEvents]], but does not impact the vast majority of existing content. In addition to matching typical platform UX conventions, this design for implicit capture enables user agents to make a performance optimization which prevents the need to invoke hit-testing on touch movement events without explicit developer opt-in (consistent with the performance properties of existing dominant native and web APIs for touch input).
In addition, user agents may implement implicit pointer capture behavior for all input devices on specific UI widgets such as input range controls (allowing some finger movement to stray outside of the form control itself during the interaction).

Implicit Release of Pointer Capture

Immediately after firing the pointerup or pointercancel events, a user agent MUST clear the pending pointer capture target override for the pointerId of the pointerup or pointercancel event that was just dispatched, and then run Process Pending Pointer Capture steps to fire lostpointercapture if necessary.

When the pointer capture target override is removed from its ownerDocument's tree, clear the pending pointer capture target override and pointer capture target override nodes and fire a PointerEvent named lostpointercapture at the document.

Compatibility Mapping with Mouse Events

The vast majority of web content existing today codes only to Mouse Events. The following describes an algorithm for how a user agent MAY map generic pointer input to mouse events for compatibility with this content.

The compatibility mapping with mouse events are an OPTIONAL feature of this specification. User agents are encouraged to support the feature for best compatibility with existing legacy content. User agents that do not support compatibility mouse events are still encouraged to support the click and contextmenu events (see the note below).

The click event, defined in [[DOM-LEVEL-3-EVENTS]], and the contextmenu event, defined in [[HTML5]], are not considered compatibility mouse events as they are typically tied to user interface activation and are fired from other input devices, like keyboards.

In user agents that support firing click and/or contextmenu, calling preventDefault during a pointer event typically does not have an effect on whether click and/or contextmenu are fired or not. Because they are not compatibility mouse events, user agents typically fire click and contextmenu for all pointing devices, including pointers that are not primary pointers.

The relative ordering of these high-level events (click, contextmenu, focus, blur, etc.) with pointer events is undefined and varies between user agents. For example, in some user agents contextmenu will often follow a pointerup, in others it'll often precede a pointerup or pointercancel, and in some situations it may be fired without any corresponding pointer event (such as a keyboard shortcut).

Unless otherwise noted, the target of any mapped mouse event SHOULD be the same target as the respective pointer event unless the target is no longer participating in its ownerDocument's tree. In this case, the mouse event should be fired at the original target's nearest ancestor node (at the time it was removed from the tree) that still participates in its ownerDocument's tree, meaning that a new event path (based on the new target node) is built for the mouse event.

Authors can prevent the production of certain compatibility mouse events by canceling the pointerdown event.

Mouse events can only be prevented when the pointer is down. Hovering pointers (e.g. a mouse with no buttons pressed) cannot have their mouse events prevented. And, the mouseover, mouseout, mouseenter, and mouseleave events are never prevented (even if the pointer is down).

Tracking the effective position of the legacy mouse pointer

While only the primary pointers can produce compatibility mouse events, multiple primary pointers can be active simultaneously, each producing its own compatibility mouse events. Since all these compatibility events would appear to MouseEvent code to be coming from a single mouse device, user agents are encouraged to guarantee that the compatibility mouse events are consistent from a single device perspective. For mouse transition events (i.e., mouseover, mouseout, mouseenter and mouseleave), this means the entry/exit state for every event target is valid as implied by [[!DOM-LEVEL-3-EVENTS]]. Users agents SHOULD guarantee this by maintaining the effective position of the legacy mouse pointer in the document as follows.

Right before firing a pointerdown, pointerup or pointermove event, or a pointerleave event at the window, the user agent SHOULD run the following steps:

  1. Let T be the target of the pointerdown, pointerup or pointermove event being dispatched. For the pointerleave event, unset T.
  2. If T and current effective legacy mouse pointer position are both unset or they are uqual, terminate these steps.
  3. Dispatch mouseover, mouseout, mouseenter and mouseleave events as per [[!DOM-LEVEL-3-EVENTS]] for a mouse moving from the current effective legacy mouse pointer position to T. Consider an unset value of either current effective legacy mouse pointer position or T as an out-of-window mouse position.
  4. Set effective legacy mouse pointer position to T.

Mapping for devices that support hover

Whenever a user agent is to dispatch a pointer event for a device that supports hover, it SHOULD run the following steps:

  1. If the isPrimary property for the pointer event to be dispatched is false then dispatch the pointer event and terminate these steps.
  2. If the pointer event to be is dispatched is a pointerdown, pointerup or pointermove event, or a pointerleave event at the window, dispatch compatibility mouse transition events as described in Tracking the effective position of the legacy mouse pointer.
  3. Dispatch the pointer event.
  4. If the pointer event dispatched was pointerdown and the event was canceled, then set the PREVENT MOUSE EVENT flag for this pointerType.
  5. If the PREVENT MOUSE EVENT flag is not set for this pointerType and the pointer event dispatched was:
    • pointerdown, then fire a mousedown event.
    • pointermove, then fire a mousemove event.
    • pointerup, then fire a mouseup event.
    • pointercancel, then fire a mouseup event at the window.
  6. If the pointer event dispatched was pointerup or pointercancel, clear the PREVENT MOUSE EVENT flag for this pointerType.

Mapping for devices that do not support hover

Some devices, such as most touchscreens, do not support hovering a coordinate (or set of coordinates) while not in the active state. Much existing content coded to mouse events assumes that a mouse is producing the events and thus certain qualities are generally true:

Hover is sometimes used to toggle the visibility of UI elements in content designed for mouse (e.g. "hover menus"). This content is often incompatible with devices that do not support hover. This specification does not define a mapping or behavior for compatibility with this scenario. It will be considered in a future version of the specification.

This requires that user agents provide a different mapping for these types of input devices. Whenever a user agent is to dispatch a pointer event for a device that does not support hover, it SHOULD run the following steps:

  1. If the isPrimary property for the pointer event to be dispatched is false then dispatch the pointer event and terminate these steps.
  2. If the pointer event to be dispatched is pointerover and the pointerdown event has not yet been dispatched for this pointer, then fire a mousemove event (for compatibility with legacy mouse-specific code).
  3. If the pointer event to be is dispatched is a pointerdown, pointerup or pointermove event, or a pointerleave event at the window, dispatch compatibility mouse transition events as described in Tracking the effective position of the legacy mouse pointer.
  4. Dispatch the pointer event.
  5. If the pointer event dispatched was pointerdown and the event was canceled, then set the PREVENT MOUSE EVENT flag for this pointerType.
  6. If the PREVENT MOUSE EVENT flag is not set for this pointerType and the pointer event dispatched was:
    • pointerdown, then fire a mousedown event.
    • pointermove, then fire a mousemove event.
    • pointerup, then fire a mouseup event.
    • pointercancel, then fire a mouseup event at the window.
  7. If the pointer event dispatched was pointerup or pointercancel, clear the PREVENT MOUSE EVENT flag for this pointerType.

If the user agent supports both Touch Events (as defined in [[TOUCH-EVENTS]]) and Pointer Events, the user agent SHOULD NOT generate compatibility mouse events as described in this section as it is likely to introduce compatibility problems for sites that expect mouse events to be generated in accordance with the model outlined in [[TOUCH-EVENTS]].

The activation of an element (click) with a primary pointer that does not support hover (e.g. single finger on a touchscreen) would typically produce the following event sequence:

  1. mousemove
  2. pointerover
  3. pointerenter
  4. mouseover
  5. mouseenter
  6. pointerdown
  7. mousedown
  8. Zero or more pointermove and mousemove events, depending on movement of the pointer
  9. pointerup
  10. mouseup
  11. click
  12. pointerout
  13. pointerleave
  14. mouseout
  15. mouseleave

If, however, the pointerdown event is canceled during this interaction then the sequence of events would be:

  1. mousemove
  2. pointerover
  3. pointerenter
  4. mouseover
  5. mouseenter
  6. pointerdown
  7. Zero or more pointermove events, depending on movement of the pointer
  8. pointerup
  9. click
  10. pointerout
  11. pointerleave
  12. mouseout
  13. mouseleave

Acknowledgments

Many thanks to lots of people for their proposals and recommendations, some of which are incorporated into this document. The group's Chair acknowledges contributions from the following group members: Arthur Barstow, Matt Brubeck, Rick Byers, Cathy Chan, Scott González, Patrick H. Lauke, Sangwhan Moon, Olli Pettay, Jacob Rossi, Doug Schepers and Asir Vedamuthu.

Special thanks to those that helped pioneer the first edition of this model, including especially: Charu Chandiram, Peter Freiling, Nathan Furtwangler, Thomas Olsen, Matt Rakow, Ramu Ramanathan, Justin Rogers, Jacob Rossi, Reed Townsend and Steve Wright.

Revision History

The following is an informative summary of substantial and major editorial changes between publications of this specification, relative to the first [[PointerEvents]] specification. See the complete revision history of the Editor's Drafts of this specification.

Changes since the 24 February 2015 Recommendation