Element.setPointerCapture() - Web APIs 编辑

The setPointerCapture() method of the Element interface is used to designate a specific element as the capture target of future pointer events. Subsequent events for the pointer will be targeted at the capture element until capture is released (via Element.releasePointerCapture()).

Note: When pointer capture is set, pointerover, pointerout, pointerenter, and pointerleave events are only generated when crossing the boundary of the capture target. This has the effect of suppressing these events on all other elements.

Overview of pointer capture

Pointer capture allows events for a particular pointer event (PointerEvent) to be re-targeted to a particular element instead of the normal (or hit test) target at a pointer's location. This can be used to ensure that an element continues to receive pointer events even if the pointer device's contact moves off the element (such as by scrolling or panning).

Syntax

targetElement.setPointerCapture(pointerId);

Parameters

pointerId

The pointerId of a PointerEvent object.

Return value

This method returns undefined.

Exceptions

Exception	Explanation
NotFoundError	pointerId does not match any of the active pointers. Note: Firefox versions before Firefox 82 incorrectly throw InvalidPointerId.

Example

This example sets pointer capture on a <div> when you press down on it. This lets you slide the element horizontally, even when you pointer moves outside of its boundaries.

HTML

<div id="slider">SLIDE ME</div>

CSS

div {
  width: 140px;
  height: 50px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: #fbe;
}

JavaScript

function beginSliding(e) {
  slider.onpointermove = slide;
  slider.setPointerCapture(e.pointerId);
}

function stopSliding(e) {
  slider.onpointermove = null;
  slider.releasePointerCapture(e.pointerId);
}

function slide(e) {
  slider.style.transform = `translate(${e.clientX - 70}px)`;
}

const slider = document.getElementById('slider');

slider.onpointerdown = beginSliding;
slider.onpointerup = stopSliding;

Result

Specifications

Specification	Status	Comment
Pointer Events – Level 2 The definition of 'setPointerCapture' in that specification.	Recommendation	Non-stable version.
Pointer Events The definition of 'setPointerCapture' in that specification.	Obsolete	Initial definition.

Browser compatibility

BCD tables only load in the browser

See also

• Element.releasePointerCapture
• Pointer Events