index.html

<script src="stockfish.js"></script>
<script>
Stockfish().then(sf => {
  window.sf = sf;

  var depth = 5;
  var listener = function (line) {
    console.log('>', line);
    if (line.includes('bestmove') && depth < 25) {
      depth++;
      console.log('============ DEPTH ' + depth + ' ============');
      sf.postMessage('go depth ' + depth);
    }
  };

  sf.addMessageListener(listener);
  //sf.removeMessageListener(listener);

  sf.postMessage('uci');
  sf.postMessage('setoption name UCI_AnalyseMode value true');
  sf.postMessage('setoption name Analysis Contempt value Off');
  setTimeout(() => {
    console.log('============ START ============');
    sf.postMessage('setoption name Threads value 32');
    sf.postMessage('setoption name Hash value 1024');
    sf.postMessage('position fen 4r1k1/r1q2ppp/ppp2n2/4P3/5Rb1/1N1BQ3/PPP3PP/R5K1 w - - 1 17');
    sf.postMessage('go depth ' + depth);
  }, 3000);
});
</script>