The element read-only property of the CSSPseudoElement interface returns a reference to the originating element of the pseudo-element, in other words its parent element.
An Element representing the pseudo-element's originating element.
The example below demonstrates the relationship between CSSPseudoElement.element and Element.pseudo():
const myElement = document.querySelector("q");
const cssPseudoElement = myElement.pseudo("::after");
const originatingElement = cssPseudoElement.element;
console.log(myElement === originatingElement);
console.log(myElement.parentElement === originatingElement);
console.log(myElement.lastElementChild === cssPseudoElement);
console.log(myElement.lastChild === cssPseudoElement);
console.log(myElement.nextElementSibling === cssPseudoElement);
console.log(myElement.nextSibling === cssPseudoElement);