Form Validation with Bootstrap

Bootstrap includes built-in validation styles.

Basic Example

<form class="needs-validation" novalidate>
  <div class="mb-3">
    <label for="username" class="form-label">Username</label>
    <input type="text" class="form-control" id="username" required>
    <div class="invalid-feedback">
      Please enter a username.
    </div>
  </div>
</form>

Add .was-validated to show validation feedback after submit.