HTML Code

<!DOCTYPE html>

<html lang="en">

<head>

  <meta charset="utf-8">

  <title>.focusout(eventData, handler)</title>

  <style>

    body { font-family: sans-serif; padding: 16px; max-width: 400px; }

    label { display: block; margin-bottom: 6px; font-weight: 600; }

    input { width: 100%; padding: 10px 12px; border: 2px solid #cbd5e1; border-radius: 6px; font-size: 16px; box-sizing: border-box; margin-bottom: 12px; }

    input.required-missing { border-color: #dc2626; background: #fef2f2; }

    #out { padding: 10px; background: #eff6ff; border-radius: 6px; color: #1e40af; font-family: monospace; font-size: 14px; min-height: 1.2em; }

  </style>

</head>

<body>

  <form id="profile-form">

    <label for="fname">First name</label>

    <input type="text" id="fname" name="first">

    <label for="email">Email</label>

    <input type="email" id="email" name="email">

  </form>

  <div id="out">Tab out of any field inside the form.</div>

  <script src="https://code.jquery.com/jquery-3.7.1.min.js"></script>

  <script>

    $("#profile-form").focusout({ rule: "required" }, function(event) {

      if ($(event.target).is("input")) {

        var empty = $(event.target).val().trim().length === 0;

        $(event.target).toggleClass("required-missing", empty);

      }

      $("#out").text("Focusout on form | rule: " + event.data.rule);

    });

  </script>

</body>

</html>

Lines: 0 | Characters: 0

Live Preview Auto-refresh on Run

jQuery .focusout(eventData, handler) — form validation (Try It)