laroportalen_keyboard_nav.js

document.addEventListener("keyup", ev => {
  const chapters = document.querySelectorAll("a.lesson-link");

  const kc = ev.key - "0";
  if (!isNaN(kc) && kc >= 0 && kc <= chapters.length) {
    chapters[kc].click();
    return;
  }

  let ci = 0;
  for (; ci < chapters.length && !chapters[ci].classList.contains("lesson-link--active"); ++ci);

  if (ci === chapters.length)
    return;

  if (ev.key === "ArrowLeft" && ci > 0)
    chapters[ci-1].click();
  else if (ev.key === "ArrowRight" && ci < chapters.length - 1)
    chapters[ci+1].click();
});