Accessibility

@# Accessibility

Blueprint strives to provide accessible components out of the box. Many of the JS components will apply accessible HTML attributes to support different modes of usage.

@## Focus management

Focus states (that glowy blue outline around the active element) are essential for keyboard navigation to indicate which element is currently active. They are less important, and occasionally outright intrusive, when using a mouse because you can click wherever you want at any time.

Blueprint includes a utility that manages the appearance of focus styles. When enabled, focus styles will be hidden while the user interacts using the mouse and will appear when the <kbd>tab</kbd> key is pressed to begin keyboard navigation. Try this out for yourself below.

You must explictly enable this feature in your app (and you probably want to):

import { FocusStyleManager } from "@blueprintjs/core";

FocusStyleManager.onlyShowFocusOnTabs();

Note that the focus style for text inputs (a slightly thicker colored border) is not removed by this utility because it is always useful to know where you're typing.

@reactExample FocusExample

@### JavaScript API

This behavior is controlled by a singleton instance called FocusStyleManager that lives in the @blueprintjs/core package. It supports the following public methods:

• FocusStyleManager.isActive(): boolean: Returns whether the FocusStyleManager is currently running.
• FocusStyleManager.onlyShowFocusOnTabs(): void: Enable behavior which hides focus styles during mouse interaction.
• FocusStyleManager.alwaysShowFocus(): void: Stop this behavior (focus styles are always visible).

@### Ignoring focus style manager

There is an escape hatch to allow components to selectively ignore the focus style manager. This can be useful when you do want to always show the focus outline, but only for certain components, like a tree. This is done by applying Classes.FOCUS_STYLE_MANAGER_IGNORE to a container element.

import { Classes } from "@blueprintjs/core";

const MyComponent = () => ({
    <div classname={Classes.FOCUS_STYLE_MANAGER_IGNORE}>
        // Any components here will always show the focus outline when clicked.
    </div>
})

@## Color contrast

Colors have been designed to be accessible to as many people as possible, even those who are visually impaired or experiencing any kind of colorblindness. Our colors have not only been chosen to go well together, but to also adhere to WCAG 2.0 standards.

@### Focus indication contrast Focus indication states generally adhere to WCAG 2.2 focus appearance. Default focus indication states should support a minimum 3:1 contrast ratio on background colors up to $light-gray1 in light theme, and $dark-gray5 in dark theme.

Components that appear with an intent outline, such as InputGroup, EditableText, NumericInput, and other similarly styled components have some exceptions to this rule. In light theme, all intents support a minimum contrast ratio of 3:1 for the full range of background colors up to $light-gray1, besides "warning", which supports a 3:1 contrast ratio up to $light-gray4. In dark theme, all intents support a minimum contrast ratio of 3:1 up to $dark-gray4, expect for "warning", which supports the full range of background colors up to $dark-gray5.