Validation

How it works in Bootstrap

  • HTML form validation is applied via CSS’s two pseudo-classes, :invalid and :valid. It applies to <input>, <select>, and <textarea> elements.
  • Bootstrap scopes the :invalid and :valid styles to parent .was-validated class, usually applied to the <form>. Otherwise, any required field without a value shows up as invalid on page load. This way, you may choose when to activate them (typically after form submission is attempted).
  • To reset the appearance of the form (for instance, in the case of dynamic form submissions using AJAX), remove the .was-validated class from the <form> again after submission.
  • As a fallback, .is-invalid and .is-valid classes may be used instead of the pseudo-classes for server-side validation. They do not require a .was-validated parent class.
  • Due to constraints in how CSS works, Bootstrap cannot (at present) apply styles to a <label> that comes before a form control in the DOM without the help of custom JavaScript.
  • All modern browsers support the constraint validation API, a series of JavaScript methods for validating form controls.
  • Feedback messages may utilize the browser defaults (different for each browser, and unstylable via CSS) or our custom feedback styles with additional HTML and CSS.
  • You may provide custom validity messages with setCustomValidity in JavaScript.

What’s changed in Material Style

  • Since we use .form-floating for our Text and Select fields, feedback messages .valid-feedback and .invalid-feedback must be kept outside the .form-floating block.
  • To apply the styles on feeback messages, we apply the .is-invalid and .is-valid classes on .form-floating and .was-validated class is also required.
  • To reset the appearance of the form, classes .is-valid and .is-invalid have to be removed as well, along with .was-validated.
  • As the <label> comes after a form control in .form-floating, styling the <label> is no longer a constraint.

Validation styles

For custom form validation messages, you’ll need to add the novalidate boolean attribute to your <form>. This disables the browser default feedback tooltips, but still provides access to the form validation APIs in JavaScript.

Try to submit the form below; our JavaScript (provided after the demo) will intercept the submit button and relay feedback to you. When attempting to submit, you’ll see the :invalid and :valid styles applied to your form controls.

Custom feedback styles apply custom colors, borders, focus styles, and background icons to better communicate feedback.

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You must agree before submitting.
html 
<form class="needs-validation d-flex flex-wrap gap-2" novalidate>

  <div>
    <div class="form-floating">
      <input type="text" class="form-control" id="textfield" placeholder="textfield" autocomplete="off" required>
      <label for="textfield">Text Field</label>
    </div>
    <div class="valid-feedback">Looks good!</div>
    <div class="invalid-feedback">Doesn't look good!</div>
  </div>

  <div>
    <div class="form-floating form-floating-outlined">
      <input type="text" class="form-control" id="textfieldOutlined" placeholder="textfield" autocomplete="off" required>
      <label for="textfieldOutlined">Outlined Text Field</label>
    </div>
    <div class="valid-feedback">Looks good!</div>
    <div class="invalid-feedback">Doesn't look good!</div>
  </div>

  <div class="input-group has-validation">
    <div class="form-floating">
      <input type="text" class="form-control" id="inputgroup" placeholder="inputgroup" autocomplete="off" required>
      <label for="inputgroup">Input Group</label>
    </div>
    <span class="input-group-text">
      <i class="bi bi-person-circle"></i>
    </span>
    <div class="validation-feedbacks">
      <div class="valid-feedback">Looks good!</div>
      <div class="invalid-feedback">Doesn't look good!</div>
    </div>
  </div>

  <div>
    <div class="form-floating">
      <select class="form-select" required>
        <option value=""></option>
        <option value="1">Option 1</option>
        <option value="2">Option 2</option>
        <option value="3">Option 3</option>
        <option value="4">Option 4</option>
      </select>
      <label>Select</label>
    </div>
    <div class="valid-feedback">Looks good!</div>
    <div class="invalid-feedback">Doesn't look good!</div>
  </div>

  <div>
    <div class="form-floating form-floating-outlined">
      <select class="form-select" required>
        <option value=""></option>
        <option value="1">Option 1</option>
        <option value="2">Option 2</option>
        <option value="3">Option 3</option>
        <option value="4">Option 4</option>
      </select>
      <label>Outlined Select</label>
    </div>
    <div class="valid-feedback">Looks good!</div>
    <div class="invalid-feedback">Doesn't look good!</div>
  </div>

  <div class="input-group has-validation">
    <div class="form-floating">
      <select class="form-select" required>
        <option value=""></option>
        <option value="1">Option 1</option>
        <option value="2">Option 2</option>
        <option value="3">Option 3</option>
        <option value="4">Option 4</option>
      </select>
      <label>Select with Input Group</label>
    </div>
    <div class="input-group-text">
      <i class="bi bi-star-fill"></i>
    </div>
    <div class="validation-feedbacks">
      <div class="valid-feedback">Looks good!</div>
      <div class="invalid-feedback">Doesn't look good!</div>
    </div>
  </div>

  <div class="form-check w-100">
    <input class="form-check-input" type="checkbox" value="" id="invalidCheck" required>
    <label class="form-check-label" for="invalidCheck">
      Agree to terms and conditions
    </label>
    <div class="invalid-feedback">
      You must agree before submitting.
    </div>
  </div>

  <button class="btn btn-primary" type="submit">Submit form</button>
</form>

Javascript

Example starter Javascript to disable form submission if there are invalid fields and to add the required classes .was-validated, .is-valid and .is-invalid.

function toggleValidityClasses(input, formFloating) {
  if (input.checkValidity()) {
    formFloating.classList.add("is-valid");
    formFloating.classList.remove("is-invalid");
  } else {
    formFloating.classList.add("is-invalid");
    formFloating.classList.remove("is-valid");
  }
}

(function () {
  "use strict";

  // Fetch all the forms we want to apply validation styles to
  var forms = document.querySelectorAll(".needs-validation");

  // Loop over them and prevent submission
  Array.prototype.slice.call(forms).forEach(function (form) {
    form.addEventListener(
      "submit",
      function (event) {
        if (!form.checkValidity()) {
          event.preventDefault();
          event.stopPropagation();
        }

        form.classList.add("was-validated");

        // Add is-valid or is-invalid classes to form-floating
        var formFloating = form.querySelectorAll(".form-floating");

        Array.prototype.slice
          .call(formFloating)
          .forEach(function (formFloating) {
            var input = formFloating.querySelector(
              ".form-control, .form-select"
            );

            if (input) {
              toggleValidityClasses(input, formFloating);

              input.addEventListener("keyup", function () {
                toggleValidityClasses(input, formFloating);
              });
              input.addEventListener("change", function () {
                toggleValidityClasses(input, formFloating);
              });
            }
          });
      },
      false
    );
  });
})();

Tooltips

If your form layout allows it, you can swap the .{valid|invalid}-feedback classes for .{valid|invalid}-tooltip classes to display validation feedback in a styled tooltip. Be sure to have a parent with position: relative on it for tooltip positioning.

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You must agree before submitting.
html 
<form class="needs-validation d-flex flex-wrap gap-2" novalidate>

  <div class="position-relative mb-5">
    <div class="form-floating">
      <input type="text" class="form-control" id="textfieldTooltip" placeholder="textfield" autocomplete="off" required>
      <label for="textfieldTooltip">Text Field</label>
    </div>
    <div class="valid-tooltip">Looks good!</div>
    <div class="invalid-tooltip">Doesn't look good!</div>
  </div>

  <div class="position-relative mb-5">
    <div class="form-floating form-floating-outlined">
      <input type="text" class="form-control" id="textfieldOutlinedTooltip" placeholder="textfield" autocomplete="off" required>
      <label for="textfieldOutlinedTooltip">Outlined Text Field</label>
    </div>
    <div class="valid-tooltip">Looks good!</div>
    <div class="invalid-tooltip">Doesn't look good!</div>
  </div>

  <div class="input-group has-validation position-relative mb-5">
    <div class="form-floating">
      <input type="text" class="form-control" id="inputgroupTooltip" placeholder="inputgroup" autocomplete="off" required>
      <label for="inputgroupTooltip">Input Group</label>
    </div>
    <span class="input-group-text">
      <i class="bi bi-person-circle"></i>
    </span>
    <div class="validation-feedbacks">
      <div class="valid-tooltip">Looks good!</div>
      <div class="invalid-tooltip">Doesn't look good!</div>
    </div>
  </div>

  <div class="position-relative mb-5">
    <div class="form-floating">
      <select class="form-select" required>
        <option value=""></option>
        <option value="1">Option 1</option>
        <option value="2">Option 2</option>
        <option value="3">Option 3</option>
        <option value="4">Option 4</option>
      </select>
      <label>Select</label>
    </div>
    <div class="valid-tooltip">Looks good!</div>
    <div class="invalid-tooltip">Doesn't look good!</div>
  </div>

  <div class="position-relative mb-5">
    <div class="form-floating form-floating-outlined">
      <select class="form-select" required>
        <option value=""></option>
        <option value="1">Option 1</option>
        <option value="2">Option 2</option>
        <option value="3">Option 3</option>
        <option value="4">Option 4</option>
      </select>
      <label>Outlined Select</label>
    </div>
    <div class="valid-tooltip">Looks good!</div>
    <div class="invalid-tooltip">Doesn't look good!</div>
  </div>

  <div class="input-group has-validation position-relative mb-5">
    <div class="form-floating">
      <select class="form-select" required>
        <option value=""></option>
        <option value="1">Option 1</option>
        <option value="2">Option 2</option>
        <option value="3">Option 3</option>
        <option value="4">Option 4</option>
      </select>
      <label>Select with Input Group</label>
    </div>
    <div class="input-group-text">
      <i class="bi bi-star-fill"></i>
    </div>
    <div class="validation-feedbacks">
      <div class="valid-tooltip">Looks good!</div>
      <div class="invalid-tooltip">Doesn't look good!</div>
    </div>
  </div>

  <div class="form-check w-100 position-relative mb-5">
    <input class="form-check-input" type="checkbox" value="" id="invalidCheckTooltip" required>
    <label class="form-check-label" for="invalidCheckTooltip">
      Agree to terms and conditions
    </label>
    <div class="invalid-tooltip">
      You must agree before submitting.
    </div>
  </div>

  <button class="btn btn-primary" type="submit">Submit form</button>
</form>

Browser defaults

Not interested in custom validation feedback messages or writing JavaScript to change form behaviors? All good, you can use the browser defaults. Try submitting the form below. Depending on your browser and OS, you’ll see a slightly different style of feedback.

While these feedback styles cannot be styled with CSS, you can still customize the feedback text through JavaScript.

html 
<form class="d-flex flex-wrap gap-2">

  <div class="form-floating">
    <input type="text" class="form-control" id="textfieldDefault" placeholder="textfield" autocomplete="off" required>
    <label for="textfieldDefault">Text Field</label>
  </div>

  <div class="form-floating form-floating-outlined">
    <input type="text" class="form-control" id="textfieldOutlinedDefault" placeholder="textfield" autocomplete="off" required>
    <label for="textfieldOutlinedDefault">Outlined Text Field</label>
  </div>

  <div class="input-group">
    <div class="form-floating">
      <input type="text" class="form-control" id="inputgroupDefault" placeholder="inputgroup" autocomplete="off" required>
      <label for="inputgroupDefault">Input Group</label>
    </div>
    <span class="input-group-text">
      <i class="bi bi-person-circle"></i>
    </span>
  </div>

  <div class="form-floating">
    <select class="form-select" required>
      <option value=""></option>
      <option value="1">Option 1</option>
      <option value="2">Option 2</option>
      <option value="3">Option 3</option>
      <option value="4">Option 4</option>
    </select>
    <label>Select</label>
  </div>

  <div class="form-floating form-floating-outlined">
    <select class="form-select" required>
      <option value=""></option>
      <option value="1">Option 1</option>
      <option value="2">Option 2</option>
      <option value="3">Option 3</option>
      <option value="4">Option 4</option>
    </select>
    <label>Outlined Select</label>
  </div>

  <div class="input-group">
    <div class="form-floating">
      <select class="form-select" required>
        <option value=""></option>
        <option value="1">Option 1</option>
        <option value="2">Option 2</option>
        <option value="3">Option 3</option>
        <option value="4">Option 4</option>
      </select>
      <label>Select with Input Group</label>
    </div>
    <div class="input-group-text">
      <i class="bi bi-star-fill"></i>
    </div>
  </div>

  <div class="form-check w-100">
    <input class="form-check-input" type="checkbox" value="" id="invalidCheckDefault" required>
    <label class="form-check-label" for="invalidCheckDefault">
      Agree to terms and conditions
    </label>
  </div>

  <button class="btn btn-primary" type="submit">Submit form</button>
</form>
We are aware that the documentation is incomplete. While we work on it, You may refer to Bootstrap docs or help us by contributing.