Track scroll events

let scrollTracked = {
  25: false,
  50: false,
  75: false,
  100: false,
};

window.addEventListener("scroll", function () {
  const scrollPercent =
    (window.scrollY /
      (document.documentElement.scrollHeight - window.innerHeight)) *
    100;

  if (scrollPercent >= 25 && !scrollTracked[25]) {
    scrollTracked[25] = true;
    postMetric("track", "goal", { event: "scroll_25" });
  }

  if (scrollPercent >= 50 && !scrollTracked[50]) {
    scrollTracked[50] = true;
    postMetric("track", "goal", { event: "scroll_50" });
  }

  if (scrollPercent >= 75 && !scrollTracked[75]) {
    scrollTracked[75] = true;
    postMetric("track", "goal", { event: "scroll_75" });
  }

  if (scrollPercent >= 100 && !scrollTracked[100]) {
    scrollTracked[100] = true;
    postMetric("track", "goal", { event: "scroll_100" });
  }
});