@wordpress/compose/build-module/hooks/use-focusable-iframe/index.js

WordPress higher-order components (HOCs).

/**
 * External dependencies
 */

/**
 * Internal dependencies
 */
import useRefEffect from '../use-ref-effect';

/**
 * Dispatches a bubbling focus event when the iframe receives focus. Use
 * `onFocus` as usual on the iframe or a parent element.
 *
 * @return Ref to pass to the iframe.
 */
export default function useFocusableIframe() {
  return useRefEffect(element => {
    const {
      ownerDocument
    } = element;
    if (!ownerDocument) {
      return;
    }
    const {
      defaultView
    } = ownerDocument;
    if (!defaultView) {
      return;
    }

    /**
     * Checks whether the iframe is the activeElement, inferring that it has
     * then received focus, and dispatches a focus event.
     */
    function checkFocus() {
      if (ownerDocument && ownerDocument.activeElement === element) {
        element.focus();
      }
    }
    defaultView.addEventListener('blur', checkFocus);
    return () => {
      defaultView.removeEventListener('blur', checkFocus);
    };
  }, []);
}
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