Replicates tabbing behavior with a function

advanceFocus.ts

/**
 * Moves focus to the next focusable element on the page, similar to pressing <Tab>
 *
 * Does not currently honor tab-indexes
 */
export function advanceFocus() {
  //Isolate the node that we're after
  const currentNode = document.activeElement;

  //find all tab-able elements
  const allElements: NodeListOf<Focusable> = document.querySelectorAll(
    "input, button, a, area, object, select, textarea"
  );

  //Find the current tab index.
  const currentIndex = [...Array.from(allElements)].findIndex(el =>
    currentNode.isEqualNode(el)
  );

  //focus the following element
  const nextIndex = (currentIndex + 1) % allElements.length;
  allElements[nextIndex].focus();
}

type Focusable =
  | HTMLInputElement
  | HTMLButtonElement
  | HTMLAnchorElement
  | HTMLAreaElement
  | HTMLObjectElement
  | HTMLTextAreaElement;