Function isFocusable

mods/spatial-navigation-polyfill.js:1002–1007

* Decide whether an element is focusable for spatial navigation. * 1. If element is the browsing context (document, iframe), then it's focusable, * 2. If the element is scrollable container (regardless of scrollable axis), then it's focusable, * 3. The value of tabIndex >= 0, then it's focu

(element)

   * @see {@link https://html.spec.whatwg.org/multipage/interaction.html#focusable-area}
   */
  function isFocusable(element) {
    if ((element.tabIndex < 0) || isAtagWithoutHref(element) || isActuallyDisabled(element) || isExpresslyInert(element) || !isBeingRendered(element))
      return false;
    else if ((!element.parentElement) || (isScrollable(element) && isOverflow(element)) || (element.tabIndex >= 0))
      return true;
  }

  /**
   * Decide whether an element is a tag without href attribute or not.