Highlight

Storybook's Highlight feature is a helpful tool for visually debugging your components. It allows you to highlight specific DOM nodes within your story when used directly or enhancing addons such as the Accessibility addon to inform you of accessibility issues within your components.

Highlighting DOM Elements

To highlight DOM elements with the feature, you'll need to emit the HIGHLIGHT event from within a story or an addon. The event payload must contain a selectors property assigned to an array of selectors matching the elements you want to highlight. For example:

Customize style

By default, highlighted elements contain a standard outline style applied to the selected elements. However, you can enable your custom style by extending the payload object with additional properties to customize the appearance of the highlighted elements. For example:

Highlight menu

The Highlight feature includes a built-in debugging option, allowing you to select the highlighted elements when you click them. This is particularly useful for inspecting the elements affected by the feature, as it lets you preview a list of elements matching the selector you provided. To enable it, add a menu property in the payload object containing additional information about the elements or trigger actions. Each item must include an id and a title, and you can also provide an optional selectors property to limit the menu item to specific highlighted elements.

{/* prettier-ignore-end */ }

When enabled, the menu will be displayed when you click on the selected element matching your provided selectors. However, if you don't want to show any information, you can omit the items or set the menu property to an empty array to show the default menu.

Remove highlights

If you need to remove a highlight from a specific element, you can do so by emitting the REMOVE_HIGHLIGHT event and providing the id of the highlight you want to remove. For example:

Reset highlighted elements

Out of the box, Storybook automatically removes highlighted elements when transitioning between stories. However, if you need to clear them manually, you can emit the RESET_HIGHLIGHT event from within a story or an addon. This removes all highlights, even ones created by other addons. For example:

Scroll element into view

The Highlight feature allows you to scroll an element into view and highlight it. To enable it, emit the SCROLL_INTO_VIEW event from within a story or an addon. The event payload must contain a selector property to target the element you want to scroll into view. When the element is visible, it will be highlighted for a brief moment.

API

Parameters

This feature contributes the following parameters to Storybook, under the highlight namespace:

disable

Type: boolean

Disable this feature's behavior. If you wish to turn off this feature for the entire Storybook, you should do so in your main configuration file.

This parameter is most useful to allow overriding at more specific levels. For example, if this parameter is set to true at the project level, it could be re-enabled by setting it to false at the meta (component) or story level.

Exports

This feature contributes the following exports to Storybook:

import { HIGHLIGHT, REMOVE_HIGHLIGHT, RESET_HIGHLIGHT, SCROLL_INTO_VIEW } from 'storybook/highlight';

HIGHLIGHT

An event to highlight DOM elements. The event payload must contain a selectors property assigned to an array of selectors matching the elements you want to highlight. It can be extended with an optional object containing additional configuration options. See the usage example above.

import { HIGHLIGHT, type HighlightOptions } from 'storybook/highlight';

channel.emit(
  HIGHLIGHT,
  options // The available configuration options inheriting from the HighlightOptions API
);

The options object contains the following properties:

interface HighlightOptions {
  /** Unique identifier for the highlight, required if you want to remove the highlight later */
  id?: string;
  /** HTML selectors of the elements */
  selectors: string[];
  /** Priority of the highlight, higher takes precedence, defaults to 0 */
  priority?: number;
  /** CSS styles to apply to the highlight */
  styles?: Record<string, string>;
  /** CSS styles to apply to the highlight when it is hovered */
  hoverStyles?: Record<string, string>;
  /** CSS styles to apply to the highlight when it is focused or selected */
  focusStyles?: Record<string, string>;
  /** Keyframes required for animations */
  keyframes?: string;
  /** Groups of menu items to show when the highlight is selected */
  menu?: HighlightMenuItem[][];
}

interface HighlightMenuItem {
  /** Unique identifier for the menu item */
  id: string;
  /** Title of the menu item */
  title: string;
  /** Description of the menu item */
  description?: string;
  /** Icon for the menu item, left side */
  iconLeft?: "chevronLeft" | "chevronRight" | "info" | "shareAlt";
  /** Icon for the menu item, right side */
  iconRight?: "chevronLeft" | "chevronRight" | "info" | "shareAlt";
  /** Name for a channel event to trigger when the menu item is clicked */
  clickEvent?: string;
  /** HTML selectors for which this menu item should show (subset of HighlightOptions['selectors']) */
  selectors?: HighlightOptions['selectors'];
}

Menu items can specify a clickEvent to be emitted on the channel when the item is clicked. The channel event will receive two arguments: the menu item id and a ClickEventDetails object with the following properties:

interface ClickEventDetails {
  // Position and dimensions of the element on the page
  top: number;
  left: number;
  width: number;
  height: number;
  // Selector(s) which matched the element
  selectors: string[];
  // DOM element details
  element: {
    attributes: Record<string, string>;
    localName: string;
    tagName: string;
    outerHTML: string;
  };
}

To listen for this event (assuming clickEvent: 'MY_CLICK_EVENT'):

import type { ClickEventDetails } from 'storybook/highlight';

const handleClickEvent = (itemId: string, details: ClickEventDetails) => {
  // Handle the menu item click event
}

// When you have a channel instance:
channel.on('MY_CLICK_EVENT', handleClickEvent)

// Or from a decorator:
useChannel({
  MY_CLICK_EVENT: handleClickEvent,
}, [handleClickEvent])

REMOVE_HIGHLIGHT

An event that removes a previously created highlight. The event payload must contain an id property assigned to the id of the highlight you want to remove. See the usage example above.

import { REMOVE_HIGHLIGHT } from 'storybook/highlight';

channel.emit(
  REMOVE_HIGHLIGHT,
  id // The id of the previously created highlight to be removed
);

RESET_HIGHLIGHT

An event to clear all highlights from highlighted elements. See the usage example above.

import { RESET_HIGHLIGHT } from 'storybook/highlight';

channel.emit(RESET_HIGHLIGHT);

SCROLL_INTO_VIEW

An event to scroll a DOM element into view and briefly highlight it. The event payload must contain a selector property assigned to the selector of the element you want to scroll into view. Optionally, you can provide a options object to customize the scroll behavior. See the usage example above.

import { SCROLL_INTO_VIEW } from 'storybook/highlight';

channel.emit(
  SCROLL_INTO_VIEW,
  selector // Element selector to scroll into view
  options // An object inheriting from ScrollIntoViewOptions API to customize the scroll behavior
);