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A design structure to organize and hide content, so as not to overwhelm the user.

Modals provide an opportunity to display content, focused actions or alerts while maintaining the context of an existing view. This limits workflow interruptions and allows for focused communication and user interactions. There are two types of modals in Base – default and alert. Each modal share the same anatomy of a header, footer, and shaded background overlay.

Standard modals are basic containers with a close “X” and the ability the dismiss by clicking outside of the modal bounds. The primary action button is a primary system color, complimented by a grey cancel action.

The alert modal is to intended to focus the user on an urgent message that requires deliberate action. By contrast to standard modals, alert modals have no close “X”, nor do they allow for out of bounds dismissal. The primary action is always a system red with a grey cancel action.


We have built in functionality based on the recommendations for dialogs and modals in WAI-ARIA Authoring Practices 1.1.

  • Upon opening, focus will be transferred to the first interactive element (unless autofocus is set to false)
  • Dialog element has aria-modal="true"
  • Explicitly exposes a role prop to control whether dialog or alertdialog is used.
  • Tab key moves between focusable items (form inputs, footer buttons, etc). User should not be able to tab to items outside of modal.
  • Escape key closes the modal
  • Click on backdrop (anywhere outside dialog) hides modal.
  • Background is not be scrollable while modal is open (position: fixed).
  • Upon closing, focus should return to element that triggered modal.


Placing initial focus

The modal will by default focus the first interactive element. If you want to focus something further down in the tab order, you can use the autoFocus property. This might be useful for targeting the most common action in the modal, such as a confirmation button.

Setting the size of the modal

A typical use case for more complex modals is to increase the size of the modal. Here, we are using a combination of overrides and in-line styles to set the height of the modal to 80vh and the width to 80vw. We also set the Modal to be a column-based flex container, while the ModalBody is then set to flex 1 1 0 in order to properly space the header and footer.

Dealing with a buried interactive element

In this example, the first interactive element (a button) is buried by the modal's content. The normal behavior of the modal will be to skip past the content and focus on the interactive element. In these cases, it is recommended by WAI-ARIA to avoid skipping content and focusing on a normally non-focusable element at the top of the content (such as an h1 or p tag). Ideally, we want to avoid an abrupt shift in context both visually and for screen-readers.

You can achieve this with the FocusOnce utility component included in baseui/modal. To use it, wrap a non interactive element at the top of the modal in FocusOnce. This will allow the element to be targeted by autofocus. Once the user tabs away, the element will be removed from the tab ordering.

Adding nested modals

Notice that you need to handle modals closing order following their stacking order when multiple modals are dismissed at the same time. This is important to have the body scrolling restored in an expected way. See how the initial modal's close function is passed as a callback to the modal that is stacked on top of it toggleConfirm(false, close).


You can import this module like so:

import {Modal} from 'baseui/modal'

It exports the following components or utility functions: