3275ca4b30
...as touch is not exclusive to "mobile" anymore nowadays. also explicitly clarifies this is a fix for iOS, and that it impacts touch laptops etc as well. lastly, renames the variable from "dropdown" to "backdrop" for clarity/consistency
22 KiB
| layout | title | description | group |
|---|---|---|---|
| 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}
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 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 %}
Dropup variation
Trigger dropdown menus above elements by adding .dropup to the parent element.
{% highlight html %}
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 %}
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 %}
Menu headers
Add a header to label sections of actions in any dropdown menu.
{% example html %}
{% 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.
On touch-enabled devices, opening a dropdown adds a .dropdown-backdrop as a tap area for closing dropdown menus when tapping outside the menu, to work around a quirk in iOS' event delegation. This means that once a dropdown menu is open, any tap or click (including with a mouse, on a multi-input device such as a laptop with a touchscreen) outside of the menu will be intercepted to close the menu. Opening another dropdown menu, or activating any other control or link, will therefore require an extra tap or click.
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 %}
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
None.
Methods
| Method | Description |
|---|---|
$().dropdown('toggle') |
Toggles the dropdown menu of a given navbar or tabbed navigation. |
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 %}