Bootstrap provides several form control styles, layout options, and custom components for creating a wide variety of forms.
## Contents
* Will be replaced with the ToC, excluding the "Contents" header
{:toc}
## Form controls
Bootstrap's form controls expand on [our Rebooted form styles]({{ site.baseurl }}/content/reboot/#forms) with classes. Use these classes to opt into their customized displays for a more consistent rendering across browsers and devices. The example form below demonstrates common HTML form elements that receive updated styles from Bootstrap with additional classes.
Remember, since Bootstrap utilizes the HTML5 doctype, **all inputs must have a `type` attribute**.
<smallid="fileHelp"class="form-text text-muted">This is some placeholder block-level help text for the above input. It's a bit lighter and easily wraps to a new line.</small>
Below is a complete list of the specific form controls supported by Bootstrap and the classes that customize them. Additional documentation is available for each group.
<table>
<thead>
<tr>
<th>Classes</th>
<th>Used for</th>
<th>Supported variations</th>
</tr>
</thead>
<tbody>
<tr>
<td>
{% markdown %}`.form-group`{% endmarkdown %}
</td>
<tdclass="text-nowrap">
Any group of form controls
</td>
<td>
{% markdown %}Use with any block-level element like `<fieldset>` or `<div>`{% endmarkdown %}
Since Bootstrap applies `display: block` and `width: 100%` to almost all our form controls, forms will by default stack vertically. Additional classes can be used to vary this layout on a per-form basis.
### Form groups
The `.form-group` class is the easiest way to add some structure to forms. Its only purpose is to provide `margin-bottom` around a label and control pairing. As a bonus, since it's a class you can use it with `<fieldset>`s, `<div>`s, or nearly any other element.
Use the `.form-inline` class to display a series of labels, form controls, and buttons on a single horizontal row. Form controls within inline forms behave differently:
- Controls are `display: inline-block` to provide alignment control via `vertical-align` and `margin`.
- Controls receive `width: auto` to override the Bootstrap default `width: 100%`.
- Controls **only appear inline in viewports that are at least 768px wide** to account for narrow viewports on mobile devices.
Because of this, you may need to manually address the width and alignment of individual form controls. Lastly, as shown below, you should always include a `<label>` with each form control.
Assistive technologies such as screen readers will have trouble with your forms if you don't include a label for every input. For these inline forms, you can hide the labels using the `.sr-only` class. There are further alternative methods of providing a label for assistive technologies, such as the `aria-label`, `aria-labelledby` or `title` attribute. If none of these are present, assistive technologies may resort to using the `placeholder` attribute, if present, but note that use of `placeholder` as a replacement for other labelling methods is not advised.
For more structured form layouts that are also responsive, you can utilize Bootstrap's [predefined grid classes](/layout/grid/#predefined-classes) or [mixins](/layout/grid/#sass-mixins) to create horizontal forms. Add the `.row` class to form groups and use the `.col-*-*` classes to specify the width of your labels and controls.
Be sure to add `.col-form-label` to your `<label>`s as well so they're vertically centered with their associated form controls. For `<legend>` elements, you can use `.col-form-legend` to make them appear similar to regular `<label>` elements.
Default checkboxes and radios are improved upon with the help of `.form-check`, **a single class for both input types that improves the layout and behavior of their HTML elements**. Checkboxes are for selecting one or several options in a list, while radios are for selecting one option from many.
Disabled checkboxes and radios are supported, but to provide a `not-allowed` cursor on hover of the parent `<label>`, you'll need to add the `.disabled` class to the parent `.form-check`. The disabled class will also lighten the text color to help indicate the input's state.
Groups of checkboxes or radios that appear on the same horizontal row are similar to their stacked counterparts, but require different HTML and a single class. To switch from stacked to inline, drop the surrounding `<div>`, add `.form-check-inline` to the `<label>`, and keep the `.form-check-input` on the `<input>`.
Should you have no text within the `<label>`, the input is positioned as you'd expect. **Currently only works on non-inline checkboxes and radios.** Remember to still provide some form of label for assistive technologies (for instance, using `aria-label`).
By default, browsers will treat all native form controls (`<input>`, `<select>` and `<button>` elements) inside a `<fieldset disabled>` as disabled, preventing both keyboard and mouse interactions on them. However, if your form also includes `<a ... class="btn btn-*">` elements, these will only be given a style of `pointer-events: none`. As noted in the section about [disabled state for buttons](../buttons/#disabled-state) (and specifically in the sub-section for anchor elements), this CSS property is not yet standardized and isn't fully supported in Opera 18 and below, or in Internet Explorer 11, and won't prevent keyboard users from being able to focus or activate these links. So to be safe, use custom JavaScript to disable such links.
{% endcallout %}
{% callout danger %}
#### Cross-browser compatibility
While Bootstrap will apply these styles in all browsers, Internet Explorer 11 and below don't fully support the `disabled` attribute on a `<fieldset>`. Use custom JavaScript to disable the fieldset in these browsers.
{% endcallout %}
## Readonly inputs
Add the `readonly` boolean attribute on an input to prevent modification of the input's value. Read-only inputs appear lighter (just like disabled inputs), but retain the standard cursor.
Block-level help text in forms can be created using `.form-text` (previously known as `.help-block` in v3). Inline help text can be flexibly implemented using any inline HTML element and utility classes like `.text-muted`.
Help text should be explicitly associated with the form control it relates to using the `aria-describedby` attribute. This will ensure that assistive technologies – such as screen readers – will announce this help text when the user focuses or enters the control.
Block help text—for below inputs or for longer lines of help text—can be easily achieved with `.form-text`. This class includes `display: block` and adds some top margin for easy spacing from the inputs above.
- To use, add `.has-warning`, `.has-danger`, or `.has-success` to the parent element. Any `.col-form-label`, `.form-control`, or custom form element will receive the validation styles.
- Contextual validation text, in addition to your usual form field help text, can be added with the use of `.form-control-feedback`. This text will adapt to the parent `.has-*` class. By default it only includes a bit of `margin` for spacing and a modified `color` for each state.
Generally speaking, you'll want to use a particular state for specific types of feedback:
- **Danger** is great for when there's a blocking or required field. A user *must* fill in this field properly to submit the form.
- **Warning** works well for input values that are in progress, like password strength, or soft validation before a user attempts to submit a form.
- And lastly, **success** is ideal for situations when you have per-field validation throughout a form and want to encourage a user through the rest of the fields.
Here are some examples of the aforementioned classes in action.
#### Conveying validation state to assistive technologies and colorblind users
Using these validation styles to denote the state of a form control only provides a visual, color-based indication, which will not be conveyed to users of assistive technologies - such as screen readers - or to colorblind users.
Ensure that an alternative indication of state is also provided. For instance, you can include a hint about state in the form control's `<label>` text itself (as is the case in the following code example), include a [Glyphicon](../components/#glyphicons) (with appropriate alternative text using the `.sr-only` class - see the [Glyphicon examples](../components/#glyphicons-examples)), or by providing an additional [help text](#forms-help-text) block. Specifically for assistive technologies, invalid form controls can also be assigned an `aria-invalid="true"` attribute.
For even more customization and cross browser consistency, use our completely custom form elements to replace the browser defaults. They're built on top of semantic and accessible markup, so they're solid replacements for any default form control.
### Checkboxes and radios
Each checkbox and radio is wrapped in a `<label>` for three reasons:
- It provides a larger hit areas for checking the control.
- It provides a helpful and semantic wrapper to help us replace the default `<input>`s.
- It triggers the state of the `<input>` automatically, meaning no JavaScript is required.
We hide the default `<input>` with `opacity` and use the `.custom-control-indicator` to build a new custom form indicator in its place. Unfortunately we can't build a custom one from just the `<input>` because CSS's `content` doesn't work on that element.
We use the sibling selector (`~`) for all our `<input>` states—like `:checked`—to properly style our custom form indicator. When combined with the `.custom-control-description` class, we can also style the text for each item based on the `<input>`'s state.
In the checked states, we use **base64 embedded SVG icons** from [Open Iconic](https://useiconic.com/open). This provides us the best control for styling and positioning across browsers and devices.
<spanclass="custom-control-description">Check this custom checkbox</span>
</label>
{% endexample %}
Custom checkboxes can also utilize the `:indeterminate` pseudo class when manually set via JavaScript (there is no available HTML attribute for specifying it).
<spanclass="custom-control-description">Or toggle this other custom radio</span>
</label>
{% endexample %}
#### Disabled
Custom checkboxes and radios can also be disabled. Add the `disabled` boolean attribute to the `<input>` and the custom indicator and label description will be automatically styled.
<spanclass="custom-control-description">Or toggle this other custom radio</span>
</label>
</div>
{% endexample %}
### Select menu
Custom `<select>` menus need only a custom class, `.custom-select` to trigger the custom styles.
{% example html %}
<selectclass="custom-select">
<optionselected>Open this select menu</option>
<optionvalue="1">One</option>
<optionvalue="2">Two</option>
<optionvalue="3">Three</option>
</select>
{% endexample %}
Custom selects degrade nicely in IE9, receiving only a handful of overrides to remove the custom `background-image`. **Multiple selects (e.g., `<select multiple>`) are not currently supported.**
### File browser
The file input is the most gnarly of the bunch and require additional JavaScript if you'd like to hook them up with functional *Choose file...* and selected file name text.
The [`:lang()` pseudo-class](https://developer.mozilla.org/en-US/docs/Web/CSS/:lang) is used to allow for easy translation of the "Browse" and "Choose file..." text into other languages. Simply override or add entries to the `$custom-file-text` SCSS variable with the relevant [language tag](https://en.wikipedia.org/wiki/IETF_language_tag) and localized strings. The English strings can be customized the same way. For example, here's how one might add a Spanish translation (Spanish's language code is `es`):
{% highlight scss %}
$custom-file-text: (
placeholder: (
en: "Choose file...",
es: "Seleccionar archivo..."
),
button-label: (
en: "Browse",
es: "Navegar"
)
);
{% endhighlight %}
You'll need to set the language of your document (or subtree thereof) correctly in order for the correct text to be shown. This can be done using [the `lang` attribute](https://developer.mozilla.org/en-US/docs/Web/HTML/Global_attributes/lang) or the [`Content-Language` HTTP header](https://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.12), among other methods.
