calebdwilliams / delegates-focus-polyfill

A polyfill for the delegatesFocus option to HTMLElement.prototype.attachShadow

Delegates focus polyfill

This package adds support for the delegatesFocus flad to the HTMLElement.attachShadowRoot method. Setting the value to true will allow the shadow host to delegate its focus events and calls to the first focusable element inside the shadow DOM.

This article on MDN will illustarate how to use the feature and browser support. The syntax is as follows.

someElement.attachShadow({
  mode: 'open',
  delegatesFocus: true
});

This will also add the delegatesFocus property to the shadow root object with the value associated with the flag.

someElement.shadowRoot.delegatesFocus === true; // would evaluate to true