CSSPseudoElement

The CSSPseudoElement interface represents a pseudo-element that may be the target of an event or animated using the Web Animations API. Instances of this interface may be obtained by calling Element.pseudo().

Properties

CSSPseudoElement.element Read only

Returns the originating/parent Element of the pseudo-element.

CSSPseudoElement.type Read only

Returns the pseudo-element selector as a CSSOMString.

Methods

CSSPseudoElement implements Animatable, so it has the following methods available to it:

Animatable.animate()

A shortcut method to create and run an animation on a pseudo-element. Returns the created Animation object instance.

Animatable.getAnimations()

Returns an array of Animation objects currently active on the pseudo-element.

CSSPseudoElement extends EventTarget, so it also inherits the following methods:

EventTarget.addEventListener()

Registers an event handler of a specific event type on the pseudo-element.

EventTarget.dispatchEvent()

Dispatches an event to this pseudo-element.

EventTarget.removeEventListener()

Removes an event listener from the pseudo-element.

Examples

Basic example using Element.pseudo

Using pseudo-elements, most modern browsers will automatically add quotation marks around text inside a <q> element. (A style rule may be needed to add quotation marks in older browsers.) The example below would cause the opening quotation mark of the first <q> element in the page to flash red twice in a row.

const element = document.querySelector('q');
const cssPseudoElement = element.pseudo('::before');
myAnimation(cssPseudoElement);

function myAnimation(cssPseudoElement) {
	let color;
	switch (cssPseudoElement.type) {
		case '::before':
			color = 'red';
			break;
		case '::after':
			color = 'green';
			break;
		default:
			color = 'blue';
			break;
	}
	cssPseudoElement.animate([
		{ color: 'currentColor' },
		{ color: color }
	], {
		duration: 250,
		direction: 'alternate',
		iterations: 4
	});
}

Adding additional animations using getAnimations()

The example below uses CSS Animations to animate the opacity of a pseudo-element, causing it to flash once per second. By calling either Document.getAnimations or Element.getAnimations, it is possible to obtain a reference to the animated CSSPseudoElement by reading the animation's effect target. In the example below, the pseudo-element will have a second animation placed upon it programmatically, causing its colour to alternate with every flash in supporting browsers.

HTML

<div></div>

CSS

div::before {
	content: "Hello, world!";
	animation-name: cssAnimation;
	animation-duration: 500ms;
	animation-direction: alternate;
	animation-iteration-count: infinite;
}

@keyframes cssAnimation {
	from {
		opacity: 0.99;
	}
	to {
		opacity: 0.2;
	}
}

JavaScript

const animations = document.getAnimations({subtree: true});
const cssPseudoElement = animations[0].effect.target;
cssPseudoElement.animate([
	{ color: 'currentColor' },
	{ color: 'red' }
], {
	duration: 1000,
	direction: 'alternate',
	iterations: Infinity
});

Result

Specifications

Browser compatibility

See also

• Element.pseudo()
• Web Animations API
• Element.animate()
• Element.getAnimations()