Some of the components we have are designed to be opened inside of the popup:
Datepicker
Dropdown
Popover
Tooltip
Typeahead
When the popup is opened, it is positioned correctly next to the target
element and fits in the
viewport. It is also possible to provide some options, ex. whether the popup should be opened to the
top
or to the bottom
of the target
element.
For instance here the tooltip is always forced to be opened to the right
, even if it won't fit in the
viewport.
Bootstrap uses popper.js
library for positioning. Before version 12.0.0
, as we did not
want to have any dependencies on 3rd party libraries, we had implemented a subset of the same functionalities
ourselves.
From version 4.1
to version 11
we positioned the popup using
position: absolute; transform: translate(x,y);
to match Bootstrap.
The position was calculated after popup opening when the zone is stable. We didn't reposition the popup on
scrolling.
Since version 12.0.0
with Bootstrap 5 support, the positioning is done with
popper v2. @popperjs/core
is defined as a peer dependency, so
be sure to include it in your package.json.
Components in question have two common inputs that help with positioning: placement
and
container
Placement
Placement specifies where the popup should be positioned in the order of preference.
Accepts an array of strings or a string with space separated values.
since 12.0.0
Possible values are "top"
,
"top-start"
, "top-left"
, "top-end"
, "top-right"
,
"bottom"
, "bottom-start"
, "bottom-left"
, "bottom-end"
,
"bottom-right"
, "start"
, "left"
, "start-top"
,
"left-top"
, "start-bottom"
, "left-bottom"
, "end"
,
"right"
, "end-top"
, "right-top"
, "end-bottom"
,
"right-bottom"
before 12.0.0
Possible values were "top"
,
"top-left"
, "top-right"
, "bottom"
, "bottom-left"
,
"bottom-right"
, "left"
, "left-top"
, "left-bottom"
,
"right"
, "right-top"
, "right-bottom"
If no placement
value is provided at all, each component has it's own default order of preference.
Check the component API docs to find out the default order, ex.
here is the tooltip's API.
There is also a special "auto"
property, that is equal to
"top", "bottom", "start", "end", "top-start", "top-end", "bottom-start", "bottom-end", "start-top",
"start-bottom", "end-top", "end-bottom"
Container
Container specifies where the popup will be physically attached to the DOM.
By default it is attached as a sibling of the target
element and the only optional supported container
is 'body'
.
Bootstrap 5 has an experimental support for RTL, so the popper placement will be adapted if the page is in RTL mode
with <html dir="rtl">
Consider the following example:
The first example with right
placement will always display the tooltip visually on the right regardless
of page direction.
The second example with end
placement will take into account page direction and display the tooltip
visually on the right by default and on the left in case of RTL direction.
This stays true for all placements containing right
, left
, start
or
end
There are two things that make dropdown a bit special at the moment: it won't be positioned dynamically when inside the navbar and the popup (dropdown menu) is always attached to the DOM.
When dropdown is used inside the Bootstrap's navbar
, it will not be positioned (to match Bootstrap
behaviour and work fine on mobile). You can override it by using the display
input.
As Dropdown
is not a component, but a set of directives, the dropdown menu popup is always attached
to the DOM even when not visible. Depending on the container
input, the menu will always be
attached either to the body or to the dropdown element.