sanderling/test/browser/testdata/counter/index.html

<!doctype html>
<html>
  <head>
    <meta charset="utf-8" />
    <title>counter</title>
  </head>
  <body>
    <button id="decrement">-</button>
    <div id="counter">0</div>
    <button id="increment">+</button>
    <script>
      let value = 0;
      const display = document.getElementById("counter");
      function render() {
        display.textContent = String(value);
      }
      document.getElementById("increment").addEventListener("click", function () {
        value += 1;
        render();
      });
      document.getElementById("decrement").addEventListener("click", function () {
        value -= 1;
        render();
      });
    </script>
  </body>
</html>