web api instance method
CSSPseudoElement: pseudo() method
Limited availability
The pseudo() method of the CSSPseudoElement interface returns a CSSPseudoElement instance representing a specific nested pseudo-element.
Syntax
pseudo(type)
Parameters
type
Return value
A CSSPseudoElement object instance, or null if type is not equal to a valid pseudo-element type.
Description
The CSSPseudoElement.pseudo() method is used to target a pseudo-element that is attached to another pseudo-element, rather than directly to a standard DOM element. For example, if a ::before pseudo-element generates a list marker — selectable via ::before::marker — this method can retrieve the ::marker nested inside that ::before. You call the method on the parent pseudo-element and pass the type of the nested child pseudo-element as an argument.
Provided its type parameter contains a valid pseudo-element type, pseudo() will always return a CSSPseudoElement instance, even if that pseudo-element hasn’t been generated on the calling pseudo-element.
Examples
Basic usage
In this example, we demonstrate basic usage of the pseudo() method.
HTML
We include a <p> element containing text, and an <output> element to log output from JavaScript.
<p>New York's hottest club is...</p>
<output></output>
CSS
We give the <p> element’s ::after pseudo-element some content and set its display to list-item so it will generate a ::marker. We also apply some basic styles.
body {
width: 80%;
margin: 0 auto;
}
p {
background-color: violet;
padding: 20px;
}
p::after {
content: "Crease";
background-color: cadetblue;
padding: 20px;
display: list-item;
}
p::after::marker {
content: "🔹";
}
JavaScript
In our script, we grab references to our <p> and <output> elements, and retrieve CSSPseudoElement objects via the pseudo() method representing the <p> element’s ::after pseudo-element, and the ::after pseudo-element’s ::marker pseudo-element. We then log some details of the child pseudo-element to our <output> element. We also include some rudimentary error handling via a try...catch structure, to print an error message in non-supporting browsers.
const pElem = document.querySelector("p");
const output = document.querySelector("output");
try {
const pseudoElem = pElem.pseudo("::after");
const pseudoPseudoElem = pseudoElem.pseudo("::marker");
output.textContent = `${pseudoPseudoElem.type} pseudo-element. Parent: ${pseudoPseudoElem.parent.type}. Ultimate originating element: <${pseudoPseudoElem.element.tagName.toLowerCase()}>`;
} catch (e) {
output.textContent = `Your browser doesn't support CSSPseudoElement and/or the pseudo() method: ${e}`;
}