Function go

lib/big.js:229–289

* The central navigation method: given a slide number, it goes to that slide * and sets it up. * * @param {number} n slide index * @param {boolean} dontSeek whether to seek audio. Specifically, when the slide * is changing _because_ of audio tracks, we don't also want to skip audio.

(n, dontSeek, force)

   * is changing _because_ of audio tracks, we don't also want to skip audio.
   */
  function go(n, dontSeek, force) {
    // Ensure that the slide we're going to is in range: it isn't
    // less than 0 or higher than the actual number of slides available.
    n = Math.max(0, Math.min(big.length - 1, n));
    // Avoid doing extra work if we're going from a slide to itself.
    if (!force && big.current === n) return;
    big.current = n;
    var slideContainer = slideDivs[n];
    var slideDiv = slideContainer.firstChild;
    printNotesToConsole(n);

    if (!dontSeek) {
      goToAudio(n);
    }

    slideDivs.forEach(function(slide, i) {
      slide.style.display = i === n ? "flex" : "none";
    });

    body.className =
      "talk-mode " +
      (slideDiv.getAttribute("data-bodyclass") || "") +
      " " +
      initialBodyClass;

    useDataImageAsBackground(slideContainer);

    // If a previous slide had set a timer to auto-advance but
    // the user navigated before it fired, cancel it.
    if (timeoutInterval !== undefined) {
      window.clearInterval(timeoutInterval);
    }

    // If this slide has a time-to-next data attribute, set a
    // timer that advances to the next slide within that many
    // seconds.
    if (slideDiv.hasAttribute("data-time-to-next")) {
      if (big.audio) {
        throw new Error(
          "this presentation uses an audio track, and also uses time-to-next. " +
            "You must only use one or the other."
        );
      }
      var timeToNextStr = slideDiv.getAttribute("data-time-to-next");
      var timeToNext = parseFloat(timeToNextStr);
      if (isNaN(timeToNext)) {
        throw new Error(
          "big encountered a bad value for the time-to-next string: " +
            timeToNextStr
        );
      }
      timeoutInterval = window.setTimeout(forward, timeToNext * 1000);
    }

    slideDiv.focus();
    onResize();
    if (window.location.hash !== n) {
      window.location.hash = n;