HTML Code

<!DOCTYPE html>



<html lang=en>



<head>



  <meta charset=UTF-8>



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



  <title>onblur — email 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}label{display:block;font-weight:600;margin-bottom:.35rem}input{width:100%;max-width:320px;padding:.5rem;font:inherit;border:1px solid #cbd5e1;border-radius:6px}.msg{margin-top:.75rem;font-size:.8125rem;max-width:320px}.msg.ok{color:#166534}.msg.err{color:#991b1b}code{background:#e2e8f0;padding:.1rem .35rem;border-radius:4px}</style>



</head>



<body>



  <h1>onblur on input</h1>



  <p>Tab out of the field or click elsewhere to run validation.</p>



  <label for=email>Email</label>



  <input type=email id=email onblur=validateEmail() placeholder=you@example.com>



  <p class=msg id=message></p>





  <script>function validateEmail(){var e=document.getElementById("email"),t=document.getElementById("message"),s=e.value.trim();t.className="msg",s?/^[^\s@]+@[^\s@]+\.[^\s@]+$/.test(s)?(t.textContent="Email looks good!",t.classList.add("ok")):(t.textContent="Please enter a valid email address.",t.classList.add("err")):(t.textContent="Email is required.",t.classList.add("err"))}</script>



</body>



</html>

Lines: 0 | Characters: 0

Live Preview Auto-refresh on Run

HTML onblur Attribute — Inline Email Validation