HTML Code
<!DOCTYPE html>
<html lang=en>
<head>
  <meta charset=UTF-8>
  <meta name=viewport content="width=device-width,initial-scale=1">
  <title>dynamic enctype</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 1rem;font-size:1.25rem;color:#0f172a}form{max-width:420px;padding:1.25rem;background:#fff;border:1px solid #e2e8f0;border-radius:8px}label{display:block;margin:.65rem 0 .25rem;font-size:.875rem;font-weight:500;color:#475569}label:first-of-type{margin-top:0}input{width:100%;box-sizing:border-box;padding:.45rem .6rem;border:1px solid #cbd5e1;border-radius:6px;font:inherit}input[type=submit]{width:auto;margin-top:.75rem;cursor:pointer}.status{margin-top:1rem;padding:.75rem 1rem;background:#fff;border:1px solid #e2e8f0;border-radius:8px;font-size:.875rem;max-width:420px}code{background:#e2e8f0;padding:.1rem .35rem;border-radius:4px}</style>
</head>
<body>
  <h1>Dynamic enctype</h1>
  <form id=dynamicForm method=post action=/submit>
    <label for=name>Name:</label>
    <input id=name name=name placeholder="Jane Doe">
    <label for=file>Choose a file (optional):</label>
    <input type=file id=file name=file>
    <input type=submit value=Submit>
  </form>
  <p class=status id=status>Current enctype: <code>application/x-www-form-urlencoded</code> (default)</p>

  <script>var form=document.getElementById("dynamicForm"),fileInput=document.getElementById("file"),status=document.getElementById("status");fileInput.addEventListener("change",(function(){fileInput.files.length>0?(form.enctype="multipart/form-data",status.innerHTML="File selected — enctype set to <code>multipart/form-data</code>."):(form.enctype="application/x-www-form-urlencoded",status.innerHTML="No file — enctype is <code>application/x-www-form-urlencoded</code>.")})),form.addEventListener("submit",(function(e){e.preventDefault(),status.innerHTML+=" Form would submit with enctype <code>"+form.enctype+"</code>."}))</script>
</body>
</html>
Lines: 0 | Characters: 0
Live Preview Auto-refresh on Run
HTML enctype Attribute — Dynamic enctype with JavaScript
