Add a tooltip to a UI element

Display additional information when focusing (or hovering over) a UI element.

Usage

tooltip(
  trigger,
  ...,
  id = NULL,
  placement = c("auto", "top", "right", "bottom", "left"),
  options = list()
)

toggle_tooltip(id, show = NULL, session = get_current_session())

update_tooltip(id, ..., session = get_current_session())

Arguments

trigger: A UI element (i.e., htmltools tag) to serve as the tooltip trigger. If trigger renders as multiple HTML elements (e.g., it's a tagList()), the last HTML element is used for the trigger. If the trigger should contain all of those elements, wrap the object in a htmltools::div() or htmltools::span().
...: UI elements for the tooltip. Character strings are automatically escaped unless marked as htmltools::HTML().
id: a character string that matches an existing tooltip id.
placement: The placement of the tooltip relative to its trigger.
options: A list of additional options.
show: Whether to show (TRUE) or hide (FALSE) the tooltip. The default (NULL) will show if currently hidden and hide if currently shown. Note that a tooltip will not be shown if the trigger is not visible (e.g., it's hidden behind a tab).
session: A Shiny session object (the default should almost always be used).

Functions

tooltip(): Add a tooltip to a UI element
toggle_tooltip(): Programmatically show/hide a tooltip.
update_tooltip(): Update the contents of a tooltip.

Theming/Styling

Like other bslib components, tooltips can be themed by supplying relevant theming variables to bs_theme(), which effects styling of every tooltip on the page. To style a specific tooltip differently from other tooltip, utilize the customClass option:

tooltip(
  "Trigger", "Tooltip message",
  options = list(customClass = "my-tip")
)

And then add relevant rules to bs_theme() via bs_add_rules():

bs_theme() |> bs_add_rules(".my-tip { max-width: none; }")

Accessibility of Tooltip Triggers

Because the user needs to interact with the trigger element to see the tooltip, it's best practice to use an element that is typically accessible via keyboard interactions, like a button or a link. If you use a non-interactive element, like a <span> or text, bslib will automatically add the tabindex="0" attribute to the trigger element to make sure that users can reach the element with the keyboard. This means that in most cases you can use any element you want as the trigger.

One place where it's important to consider the accessibility of the trigger is when using an icon without any accompanying text. In these cases, many R packages that provide icons will create an icon element with the assumption that the icon is decorative, which will make it inaccessible to users of assistive technologies.

When using an icon as the primary trigger, ensure that the icon does not have aria-hidden="true" or role="presentation" attributes. Icon packages typically provide a way to specify a title for the icon, as well as a way to specify that the icon is not decorative. The title should be a short description of the purpose of the trigger, rather than a description of the icon itself.

If you're using bsicons::bs_icon(), provide a title.
If you're using fontawesome::fa(), set a11y = "sem" and provide a title.

For example:

tooltip(
  bsicons::bs_icon("info-circle", title = "About tooltips"),
  "Text shown in the tooltip."
)

tooltip(
  fontawesome::fa("info-circle", a11y = "sem", title = "About tooltips"),
  "Text shown in the tooltip."
)

References

Tooltips are based on Bootstrap's Tooltip component. See the bslib website for an interactive introduction to tooltips and popovers.

Examples

if (FALSE) { # rlang::is_interactive()

tooltip(
  shiny::actionButton("btn", "A button"),
  "A message"
)

card(
  card_header(
    tooltip(
      span("Card title ", bsicons::bs_icon("question-circle-fill")),
      "Additional info",
      placement = "right"
    )
  ),
  "Card body content..."
)
}