HTML Code
<!DOCTYPE html>

<html lang=en>

<head>

  <meta charset=UTF-8>

  <meta name=viewport content="width=device-width,initial-scale=1">

  <title>oncuechange — vs timeupdate</title>

  <style>body{font-family:system-ui,sans-serif;margin:0;padding:1.5rem;background:#f8fafc;color:#334155;line-height:1.7}h1{margin:0 0 .75rem;font-size:1.25rem;color:#0f172a}audio{display:block;max-width:100%;width:320px;margin-bottom:.75rem}.counts{display:grid;gap:.5rem;max-width:420px}.count{padding:.75rem 1rem;border-radius:8px;font-size:.8125rem}.timeupdate{background:#fef3c7;border:1px solid #fde68a;color:#92400e}.cuechange{background:#eff6ff;border:1px solid #bfdbfe;color:#1e40af}button{margin-top:.75rem;padding:.5rem 1rem;border:1px solid #cbd5e1;border-radius:6px;background:#fff;cursor:pointer;font-size:.875rem}</style>

</head>

<body>

  <h1>cuechange vs timeupdate</h1>

  <p>Press play — timeupdate fires often; cuechange only when caption lines change.</p>

  <audio id=clip controls>

    <source src=/audio/count.mp3 type=audio/mpeg>

    <track kind=captions src=/audio/count.vtt srclang=en label=English>

  </audio>

  <div class=counts>

    <div class="count timeupdate" id=time-count>timeupdate: 0</div>

    <div class="count cuechange" id=cue-count>cuechange: 0</div>

  </div>

  <button type=button id=reset>Reset counts</button>



  <script>var audio=document.getElementById("clip"),timeCount=0,cueCount=0,timeEl=document.getElementById("time-count"),cueEl=document.getElementById("cue-count");audio.addEventListener("timeupdate",(function(){timeCount+=1,timeEl.textContent="timeupdate: "+timeCount})),audio.addEventListener("loadedmetadata",(function(){var e=audio.textTracks[0];e.mode="hidden",e.addEventListener("cuechange",(function(){cueCount+=1,cueEl.textContent="cuechange: "+cueCount}))})),document.getElementById("reset").addEventListener("click",(function(){timeCount=0,cueCount=0,timeEl.textContent="timeupdate: 0",cueEl.textContent="cuechange: 0"}))</script>

</body>

</html>
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HTML oncuechange Attribute — cuechange vs timeupdate
