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docs Dropdowns Toggle contextual overlays for displaying lists of links and more with the Bootstrap dropdown plugin. components

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.

Contents

  • Will be replaced with the ToC, excluding the "Contents" header {:toc}

Overview

Things to know when using the popover plugin:

  • Dropdown rely on the 3rd party library Popper.js for positioning. You must include popper.min.js before bootstrap.js in order for dropdowns to work!
  • Popper.js handle natively the flip of Dropdown when it's outside the viewport, if you want to disable that's behavior use flip attribute

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.

{% callout info %}

Dropdown menu 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. {% endcallout %}

Single button dropdowns

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:

{% example html %}

{% endexample %}

And with <a> elements:

{% example html %}

{% endexample %}

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

{% highlight html %}

{% endhighlight %}

Split button dropdowns

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.

{% highlight html %}

{% endhighlight %}

Sizing

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

{% highlight html %}

Large button
...
Large button Toggle Dropdown
...
Small button
...
Small button Toggle Dropdown
...
{% endhighlight %}

Dropup variation

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

{% highlight html %}

Dropup Toggle Dropdown
Split dropup Toggle Dropdown
{% 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.

{% example html %}

Dropdown
Action Another action Something else here
{% endexample %}

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.

{% callout info %} Heads up! Dropdowns are positioned only with CSS and may need some additional styles for exact alignment. {% endcallout %}

{% example html %}

This dropdown's menu is right-aligned
Action Another action Something else here
{% endexample %}

Menu headers

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

{% example html %}

Dropdown header
Action Another action
{% endexample %}

Menu dividers

Separate groups of related menu items with a divider.

{% example html %}

{% endexample %}

Disabled menu items

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

{% example html %}

{% endexample %}

Usage

Via data attributes or JavaScript, the dropdown plugin toggles hidden content (dropdown menus) by toggling the .show class on the parent list item.

{% callout info %} 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. {% endcallout %}

Note: 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.

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 %}

{% callout info %}

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. {% endcallout %}

Options

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

Name Type Default Description
placement string | function 'bottom'

How to position the popover - top | bottom.
offset number | string 0 Offset of the dropdown relative to its target. 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.

Methods

Method Description
$().dropdown('toggle') Toggles the dropdown menu of a given navbar or tabbed navigation.
$().dropdown('update') Updates the position of 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.

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 %}