Provide valuable, actionable feedback to your users with HTML5 form validation, via browser default behaviors or custom styles and JavaScript.
Note: We currently recommend using custom validation styles, as native browser default validation messages are not consistently exposed to assistive technologies in all browsers (most notably, Chrome on desktop and mobile).
For custom MDB 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 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.
// Example starter JavaScript for disabling form submissions if there are invalid fields
(function () {
'use strict';
// Fetch all the forms we want to apply custom Bootstrap 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');
},
false
);
});
})();
Here’s how form validation works with MDB:
:invalid and :valid. It applies to
<input> and <textarea> elements.
: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).
.was-validated class from the
<form> again after submission.
.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.
<label> that comes before a form control in the DOM without
the help of custom JavaScript.
setCustomValidity in JavaScript.
With that in mind, consider the following demos for our custom form validation styles, optional server-side classes, and 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.
We recommend using client-side validation, but in case you require server-side
validation, you can indicate invalid and valid form fields with
.is-invalid and .is-valid. Note that
.invalid-feedback is also supported with these classes.
Validation styles are available for the following form controls and components:
<input>s and <textarea>s with
.form-control (including up to one .form-control in
input groups)
.form-checks.form-file
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. In the example
below, our column classes have this already, but your project may require an
alternative setup.
Validation states can be customized via Sass with the
$form-validation-states map. Located in our
_variables.scss file, this Sass map is looped over to generate the
default valid/invalid validation states. Included is a
nested map for customizing each state’s color. While no other states are
supported by browsers, those using custom styles can easily add more complex
form feedback.
Please note that we do not recommend customizing these values without also
modifying the form-validation-state mixin.
This is the Sass map from _variables.scss. Override this and
recompile your Sass to generate different states:
$form-validation-states: ( "valid": ( "color": $form-feedback-valid-color,
"icon": $form-feedback-icon-valid ), "invalid": ( "color":
$form-feedback-invalid-color, "icon": $form-feedback-icon-invalid ) );
This is the loop from forms/_validation.scss.scss. Any
modifications to the above Sass map will be reflected in your compiled CSS via
this loop:
@each $state, $data in $form-validation-states { @include
form-validation-state($state, map-get($data, color), map-get($data, icon));
}
var myModal = new bootstrap.Modal(document.getElementById('myModal'), options)
| Name | Type | Default | Description |
|---|---|---|---|
tag |
String | 'button' |
Changes button tag |
| Name | Description | Example |
|---|---|---|
toggle |
Manually toggles a modal | myModal.toggle() |
| Name | Description |
|---|---|
show.bs.modal
|
This event fires immediately when the show instance method is called. If caused by a click, the clicked element is available as the relatedTarget property of the event. |