How To Validate Form Inputs Example

<!DOCTYPE html>
<html>
<head>
<title>Form Validation Example</title>
<style>
  body {
    font-family: sans-serif;
    margin: 20px;
  }
  form {
    background: #f1f1f1;
    padding: 30px;
    border-radius: 12px;
    max-width: 350px;
  }
  .form-group {
    margin-bottom: 20px;
  }
  label {
    display: block;
    margin-bottom: 8px;
    font-weight: bold;
  }
  input {
    width: 100%;
    padding: 10px;
    border: 1px solid #ccc;
    border-radius: 4px;
    box-sizing: border-box;
  }
  /* Optional: visual feedback for valid/invalid inputs */
  input:invalid {
    border-color: #ff0000;
  }
  input:valid {
    border-color: #28a745;
  }
  input[type="submit"] {
    background-color: #007bff;
    color: white;
    border: none;
    cursor: pointer;
    margin-top: 10px;
  }
  input[type="submit"]:hover {
    background-color: #0056b3;
  }
</style>
</head>
<body>

<h3>Sign Up Form</h3>
<p>Try submitting the form without filling it in, or try with an invalid email address.</p>

<form action="/html/tags/html_form_tag.cfm">
  <div class="form-group">
    <label for="username">Username (min 4 chars):</label>
    <input type="text" id="username" name="username" required minlength="4">
  </div>
  <div class="form-group">
    <label for="email">Email Address:</label>
    <input type="email" id="email" name="email" required placeholder="name@example.com">
  </div>
  <div class="form-group">
    <label for="birth-year">Birth Year (1900-2023):</label>
    <input type="number" id="birth-year" name="birth-year" min="1900" max="2023">
  </div>
  <input type="submit" value="Sign Up">
</form>

</body>
</html>