In response to Google stopping their support for the in search engine Timer, I made a stop watch app which can be a good starting point project.

stop-watch-starter.html

<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@5.1.3/dist/css/bootstrap.min.css" integrity="sha384-1BmE4kWBq78iYhFldvKuhfTAU6auU8tT94WrHftjDbrCEXSU1oBoqyl2QvZ6jIW3" crossorigin="anonymous">

<div class="container text-center">
  <h1>Stop Watch</h1>
  <button id="startStopBtn" class="btn btn-primary btn-lg">Start</button>
  <button id="resetBtn" class="btn btn-secondary btn-lg">Reset</button>
  <p id=o class="fs-1">0</p>
</div>

<script>
(() => {
  let currTime = 0;
  let startTime = 0;
  let accrued = 0;
  let interval = null;
  let go = false;
  const getCurrTime = () => new Date().getTime();
  const startStopBtn = document.getElementById("startStopBtn");
  startStopBtn.onclick = () => {
    go = !go;
    startStopBtn.innerHTML = go ? "Stop" : "Start";
    if (go) {
      startTime = new Date().getTime();
      interval = setInterval(() => {
        accrued += getCurrTime() - startTime;
      	o.innerHTML = accrued;
      }, 60);
    }
    else clearInterval(interval);
  };
  resetBtn.onclick = () => o.innerHTML = accrued = 0;
})();
</script>