twbs--bootstrap/site/docs/4.3/components/dropdowns.md

layout	title	description	group	toc
docs	Dropdowns	Toggle contextual overlays for displaying lists of links and more with the Bootstrap dropdown plugin.	components	true

Overview

Dropdowns are toggleable, contextual overlays for displaying lists of links and more. They're made interactive with the included Bootstrap dropdown JavaScript plugin. They're toggled by clicking, not by hovering; this is an intentional design decision.

Dropdowns are built on a third party library, Popper.js, which provides dynamic positioning and viewport detection. Be sure to include [popper.min.js]({{ site.cdn.popper }}) before Bootstrap's JavaScript or use bootstrap.bundle.min.js / bootstrap.bundle.js which contains Popper.js. Popper.js isn't used to position dropdowns in navbars though as dynamic positioning isn't required.

If you're building our JavaScript from source, it [requires util.js]({{ site.baseurl }}/docs/{{ site.docs_version }}/getting-started/javascript/#util).

Accessibility

The WAI ARIA standard defines an actual role="menu" widget, but this is specific to application-like menus which trigger actions or functions. ARIA menus can only contain menu items, checkbox menu items, radio button menu items, radio button groups, and sub-menus.

Bootstrap's dropdowns, on the other hand, are designed to be generic and applicable to a variety of situations and markup structures. For instance, it is possible to create dropdowns that contain additional inputs and form controls, such as search fields or login forms. For this reason, Bootstrap does not expect (nor automatically add) any of the role and aria- attributes required for true ARIA menus. Authors will have to include these more specific attributes themselves.

However, Bootstrap does add built-in support for most standard keyboard menu interactions, such as the ability to move through individual .dropdown-item elements using the cursor keys and close the menu with the ESC key.

Examples

Wrap the dropdown's toggle (your button or link) and the dropdown menu within .dropdown, or another element that declares position: relative;. Dropdowns can be triggered from <a> or <button> elements to better fit your potential needs.

Single button

Any single .btn can be turned into a dropdown toggle with some markup changes. Here's how you can put them to work with either <button> elements:

{% capture example %}

Dropdown button

Action Another action Something else here

{% endcapture %} {% include example.html content=example %}

And with <a> elements:

{% capture example %}

Dropdown link

Action Another action Something else here

{% endcapture %} {% include example.html content=example %}

The best part is you can do this with any button variant, too:

Primary

Action Another action Something else here

Separated link

Secondary

Action Another action Something else here

Separated link

Success

Action Another action Something else here

Separated link

Info

Action Another action Something else here

Separated link

Warning

Action Another action Something else here

Separated link

Danger

Action Another action Something else here

Separated link

{% highlight html %}

Action

Action Another action Something else here

Separated link

{% endhighlight %}

Split button

Similarly, create split button dropdowns with virtually the same markup as single button dropdowns, but with the addition of .dropdown-toggle-split for proper spacing around the dropdown caret.

We use this extra class to reduce the horizontal padding on either side of the caret by 25% and remove the margin-left that's added for regular button dropdowns. Those extra changes keep the caret centered in the split button and provide a more appropriately sized hit area next to the main button.

Primary Toggle Dropdown

Action Another action Something else here

Separated link

Secondary Toggle Dropdown

Action Another action Something else here

Separated link

Success Toggle Dropdown

Action Another action Something else here

Separated link

Info Toggle Dropdown

Action Another action Something else here

Separated link

Warning Toggle Dropdown

Action Another action Something else here

Separated link

Danger Toggle Dropdown

Action Another action Something else here

Separated link

{% highlight html %}

Action Toggle Dropdown

Action Another action Something else here

Separated link

{% endhighlight %}

Sizing

Button dropdowns work with buttons of all sizes, including default and split dropdown buttons.

Large button

Action Another action Something else here

Separated link

Large split button Toggle Dropdown

Action Another action Something else here

Separated link

Small button

Action Another action Something else here

Separated link

Small split button Toggle Dropdown

Action Another action Something else here

Separated link

{% highlight html %}

Large button

...

Large split button Toggle Dropdown

...

Small button

...

Small split button Toggle Dropdown

...

{% endhighlight %}

Directions

Dropup

Trigger dropdown menus above elements by adding .dropup to the parent element.

Dropup

Action Another action Something else here

Separated link

Split dropup Toggle Dropdown

Action Another action Something else here

Separated link

{% highlight html %}

Dropup

Split dropup Toggle Dropdown

{% endhighlight %}

Dropright

Trigger dropdown menus at the right of the elements by adding .dropright to the parent element.

Dropright

Action Another action Something else here

Separated link

Split dropright Toggle Dropright

Action Another action Something else here

Separated link

{% highlight html %}

Dropright

Split dropright Toggle Dropright

{% endhighlight %}

Dropleft

Trigger dropdown menus at the left of the elements by adding .dropleft to the parent element.

Dropleft

Action Another action Something else here

Separated link

Toggle Dropleft

Action Another action Something else here

Separated link

Split dropleft

{% highlight html %}

Dropleft

Toggle Dropleft

Split dropleft

{% endhighlight %}

Menu items

Historically dropdown menu contents had to be links, but that's no longer the case with v4. Now you can optionally use <button> elements in your dropdowns instead of just <a>s.

{% capture example %}

Dropdown

Action Another action Something else here

{% endcapture %} {% include example.html content=example %}

You can also create non-interactive dropdown items with .dropdown-item-text. Feel free to style further with custom CSS or text utilities.

{% capture example %}

Dropdown item text Action Another action Something else here

{% endcapture %} {% include example.html content=example %}

Active

Add .active to items in the dropdown to style them as active.

{% capture example %}

Regular link Active link Another link

{% endcapture %} {% include example.html content=example %}

Disabled

Add .disabled to items in the dropdown to style them as disabled.

{% capture example %}

Regular link Disabled link Another link

{% endcapture %} {% include example.html content=example %}

Menu alignment

By default, a dropdown menu is automatically positioned 100% from the top and along the left side of its parent. Add .dropdown-menu-right to a .dropdown-menu to right align the dropdown menu.

{% capture callout %} Heads up! Dropdowns are positioned thanks to Popper.js (except when they are contained in a navbar). {% endcapture %} {% include callout.html content=callout type="info" %}

{% capture example %}

Right-aligned menu

Action Another action Something else here

{% endcapture %} {% include example.html content=example %}

Responsive alignment

If you want to use responsive alignment, disable dynamic positioning by adding the data-display="static" attribute and use the responsive variation classes.

To align right the dropdown menu with the given breakpoint or larger, add .dropdown-menu{-sm|-md|-lg|-xl}-right.

{% capture example %}

Left-aligned but right aligned when large screen

Action Another action Something else here

{% endcapture %} {% include example.html content=example %}

To align left the dropdown menu with the given breakpoint or larger, add .dropdown-menu-right and .dropdown-menu{-sm|-md|-lg|-xl}-left.

{% capture example %}

Right-aligned but left aligned when large screen

Action Another action Something else here

{% endcapture %} {% include example.html content=example %}

Note that you don't need to add a data-display="static" attribute to dropdown buttons in navbars, since Popper.js isn't used in navbars.

Menu content

Headers

Add a header to label sections of actions in any dropdown menu.

{% capture example %}

Dropdown header

Action Another action

{% endcapture %} {% include example.html content=example %}

Dividers

Separate groups of related menu items with a divider.

{% capture example %}

Action Another action Something else here

Separated link

{% endcapture %} {% include example.html content=example %}

Text

Place any freeform text within a dropdown menu with text and use [spacing utilities]({{ site.baseurl }}/docs/{{ site.docs_version }}/utilities/spacing/). Note that you'll likely need additional sizing styles to constrain the menu width.

{% capture example %}

Some example text that's free-flowing within the dropdown menu.

And this is more example text.

{% endcapture %} {% include example.html content=example %}

Forms

Put a form within a dropdown menu, or make it into a dropdown menu, and use [margin or padding utilities]({{ site.baseurl }}/docs/{{ site.docs_version }}/utilities/spacing/) to give it the negative space you require.

{% capture example %}

Email address

Password

Remember me

Sign in

New around here? Sign up Forgot password?

{% endcapture %} {% include example.html content=example %}

{% capture example %}

Email address

Password

Remember me

Sign in {% endcapture %} {% include example.html content=example %}

Dropdown options

Use data-offset or data-reference to change the location of the dropdown.

{% capture example %}

Offset

Action Another action Something else here

Reference Toggle Dropdown

Action Another action Something else here

Separated link

{% endcapture %} {% include example.html content=example %}

Usage

Via data attributes or JavaScript, the dropdown plugin toggles hidden content (dropdown menus) by toggling the .show class on the parent list item. The data-toggle="dropdown" attribute is relied on for closing dropdown menus at an application level, so it's a good idea to always use it.

{% capture callout %} On touch-enabled devices, opening a dropdown adds empty ($.noop) mouseover handlers to the immediate children of the <body> element. This admittedly ugly hack is necessary to work around a quirk in iOS' event delegation, which would otherwise prevent a tap anywhere outside of the dropdown from triggering the code that closes the dropdown. Once the dropdown is closed, these additional empty mouseover handlers are removed. {% endcapture %} {% include callout.html content=callout type="info" %}

Via data attributes

Add data-toggle="dropdown" to a link or button to toggle a dropdown.

{% highlight html %}

Dropdown trigger

...

{% endhighlight %}

Via JavaScript

Call the dropdowns via JavaScript:

{% highlight js %} $('.dropdown-toggle').dropdown() {% endhighlight %}

{% capture callout %}

data-toggle="dropdown" still required

Regardless of whether you call your dropdown via JavaScript or instead use the data-api, data-toggle="dropdown" is always required to be present on the dropdown's trigger element. {% endcapture %} {% include callout.html content=callout type="info" %}

Options

Options can be passed via data attributes or JavaScript. For data attributes, append the option name to data-, as in data-offset="".

Name	Type	Default	Description
offset	number | string | function	0	Offset of the dropdown relative to its target. When a function is used to determine the offset, it is called with an object containing the offset data as its first argument. The function must return an object with the same structure. The triggering element DOM node is passed as the second argument. For more information refer to Popper.js's offset docs.
flip	boolean	true	Allow Dropdown to flip in case of an overlapping on the reference element. For more information refer to Popper.js's flip docs.
boundary	string | element	'scrollParent'	Overflow constraint boundary of the dropdown menu. Accepts the values of 'viewport', 'window', 'scrollParent', or an HTMLElement reference (JavaScript only). For more information refer to Popper.js's preventOverflow docs.
reference	string | element	'toggle'	Reference element of the dropdown menu. Accepts the values of 'toggle', 'parent', or an HTMLElement reference. For more information refer to Popper.js's referenceObject docs.
display	string	'dynamic'	By default, we use Popper.js for dynamic positioning. Disable this with static.

Note when boundary is set to any value other than 'scrollParent', the style position: static is applied to the .dropdown container.

Methods

Method	Description
$().dropdown('toggle')	Toggles the dropdown menu of a given navbar or tabbed navigation.
$().dropdown('show')	Shows the dropdown menu of a given navbar or tabbed navigation.
$().dropdown('hide')	Hides the dropdown menu of a given navbar or tabbed navigation.
$().dropdown('update')	Updates the position of an element's dropdown.
$().dropdown('dispose')	Destroys an element's dropdown.

Events

All dropdown events are fired at the .dropdown-menu's parent element and have a relatedTarget property, whose value is the toggling anchor element. hide.bs.dropdown and hidden.bs.dropdown events have a clickEvent property (only when the original event type is click) that contains an Event Object for the click event.

Event	Description
show.bs.dropdown	This event fires immediately when the show instance method is called.
shown.bs.dropdown	This event is fired when the dropdown has been made visible to the user (will wait for CSS transitions, to complete).
hide.bs.dropdown	This event is fired immediately when the hide instance method has been called.
hidden.bs.dropdown	This event is fired when the dropdown has finished being hidden from the user (will wait for CSS transitions, to complete).

{% highlight js %} $('#myDropdown').on('show.bs.dropdown', function () { // do something... }) {% endhighlight %}