ElementInternals: states property

The states read-only property of the ElementInternals interface returns a CustomStateSet representing the possible states of the custom element.

Value

A CustomStateSet which is a Set of strings.

Examples

The following function adds and removes the state --checked to a CustomStateSet, then prints to the console true or false as the custom checkbox is checked or unchecked.

class MyElement extends HTMLElement {
  set checked(flag) {
    if (flag) {
      this._internals.states.add("--checked");
    } else {
      this._internals.states.delete("--checked");
    }

    console.log(this._internals.states.has("--checked"));
  }
}

Specifications

Browser compatibility