HTML Code
<!DOCTYPE html>

<html lang=en>

<head>

  <meta charset=UTF-8>

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

  <title>onsubmit — login validation</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}form{max-width:420px;padding:1rem;background:#fff;border:1px solid #e2e8f0;border-radius:8px}label{display:block;margin-bottom:.25rem;font-weight:600;font-size:.875rem}input[type=password],input[type=text]{width:100%;padding:.5rem .75rem;margin-bottom:.75rem;border:1px solid #cbd5e1;border-radius:6px;box-sizing:border-box}input[type=submit]{padding:.5rem 1rem;border:none;border-radius:6px;background:#2563eb;color:#fff;font-weight:600;cursor:pointer}#status{margin-top:.75rem;padding:.75rem 1rem;border-radius:8px;font-size:.875rem;font-weight:600;max-width:420px;background:#f1f5f9;border:1px solid #e2e8f0;color:#475569}</style>

</head>

<body>

  <h1>Simple login form</h1>

  <p>Submit with empty fields to see validation feedback.</p>



  <form action=# onsubmit="return validateForm()">

    <label for=username>Username</label>

    <input id=username name=username>



    <label for=password>Password</label>

    <input type=password id=password name=password>



    <input type=submit value=Submit>

  </form>

  <p id=status aria-live=polite>Waiting for submit…</p>



  <script>function validateForm(){var e=document.getElementById("username").value.trim(),t=document.getElementById("password").value.trim(),l=document.getElementById("status");return""===e||""===t?(l.textContent="Please fill in all fields",l.style.background="#fef2f2",l.style.borderColor="#fecaca",l.style.color="#991b1b",!1):(l.textContent="Form validated — ready to send!",l.style.background="#f0fdf4",l.style.borderColor="#bbf7d0",l.style.color="#166534",!1)}</script>

</body>

</html>
Lines: 0 | Characters: 0
Live Preview Auto-refresh on Run
HTML onsubmit Attribute — inline form validation
