test touch delays

gistfile1.txt

// https://dzone.com/articles/300-ms-click-delay-and-ios-8
// https://patrickhlauke.github.io/touch/tests/results/
// https://developer.mozilla.org/en-US/docs/Web/API/Performance/measure

<button>Click</button>
<p style="color: black;">Delay was <span></span> milliseconds.</p>
<script>
  var button = document.querySelector("button"),
    span = document.querySelector("span"),
    delay;

  button.addEventListener("touchstart", function () {
    delay = Date.now();
  });

  button.addEventListener("click", function () {
    span.innerHTML = Date.now() - delay;
  });
</script>