addons-api.md

title
Addon API

Core Addon API

This is the core addon API. This is how to get the addon API:

<CodeSnippets paths={[ 'common/storybook-addons-api-imports.js.mdx', ]} />

addons.getChannel()

Get an instance to the channel where you can communicate with the manager and the preview. You can find this in both the addon register code and in your addon’s wrapper component (where used inside a story).

It has a NodeJS EventEmitter compatible API. So, you can use it to emit events and listen for events.

addons.register()

This method allows you to register an addon and get the storybook API. You can do this only in the Manager App. See how we can use this:

<CodeSnippets paths={[ 'common/storybook-addons-api-register.js.mdx', ]} />

Now you'll get an instance to our StorybookAPI. See the api docs for Storybook API regarding using that.

addons.add()

This method allows you to add a panel to Storybook. (Storybook's Action Logger is a panel). You can do this only in the Manager App. See how you can use this method:

<CodeSnippets paths={[ 'common/storybook-addon-panel-initial.js.mdx', ]} />

The render function is called with active and key.

When the panel is in focus in the UI, the active will be true.

As you can see, you can set any React Component as the panel. Currently, it's one line of text. But you can do anything you want. You should specify the panel title. It could be a plain text.

makeDecorator API

The makeDecorator API can be used to create decorators in the style of the official addons. Use it like so:

<CodeSnippets paths={[ 'common/storybook-addons-api-makedecorator.js.mdx', ]} />

The options to makeDecorator are:

• name: The name of the export (e.g. withFoo)
• parameterName: The name of the parameter your addon uses. This should be unique.
• skipIfNoParametersOrOptions: Don't run your decorator if the user hasn't set options (via .addDecorator(withFoo(options)))) or parameters (.add('story', () => <Story/>, { foo: 'param' }), or .addParameters({ foo: 'param' })).
• allowDeprecatedUsage: support the deprecated "wrapper" usage (.add('story', () => withFoo(options)(() => <Story/>))).
• wrapper: your decorator function. Takes the storyFn, context, and both the options and parameters (as defined in skipIfNoParametersOrOptions above).

Note if the parameters to a story include { foo: { disable: true } } (where foo is the parameterName of your addon), your decorator will not be called.

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Storybook hooks

Writing addons can be simplified a lot by using these Storybook hooks:

useStorybookState

<CodeSnippets paths={[ 'common/storybook-addons-api-usestorybookstate.js.mdx', ]} />

Allows full access to the entire storybook state. Your component will re-render whenever the storybook state changes.

If you use this, remember your component wil be re-rendered a lot, and you may need to optimize for that using React.memo or useMemo or PureComponent.

useStorybookApi

<CodeSnippets paths={[ 'common/storybook-addons-api-useapi.js.mdx', ]} />

Allows full access to the storybook API.

Detail on the storybook api are further down.

useChannel

<CodeSnippets paths={[ 'common/storybook-addons-api-usechannel.js.mdx', ]} />

Allows for both setting subscriptions to events and getting the emitter for emitting custom event unto the channel.

The messages can be listened for on both the iframe and the manager side.

useAddonState

<CodeSnippets paths={[ 'common/storybook-addons-api-useaddonstate.js.mdx', ]} />

Extremely useful for addons that need to persist some state.

Storybook may unmount your addon component, and so keeping local state, might not work really well.

Also some addons consist of multiple parts, some part being in a panel, some in the toolbar etc.

With this hook they can all get access to the same bit of state which is persisted even if the components are unmounted.

useParameter

<CodeSnippets paths={[ 'common/storybook-addons-api-useparameter.js.mdx', ]} />

This hook gets you the current story's parameter.

If the parameter isn't set, the default value (second argument) is returned instead.

useGlobals

<CodeSnippets paths={[ 'common/storybook-addons-api-useglobal.js.mdx', ]} />

Extremely useful hook for addons that rely on Storybook Globals.

It allows you to retrieve and update any Storybook Globals you want.

If you use this hook, remember that your component will render a lot, and you may need to optimize for that using React.memo or useMemo or useCallback.

---

Storybook API

Storybook API allows you to access different functionalities of Storybook UI. You can move an instance to the Storybook API when you register an addon.

Let's have a look at API methods.

api.selectStory()

With this method, you can select a story via an API. This method accepts two parameters.

1. story kind name
2. story name (optional)

Let's say you've got a story like this:

<CodeSnippets paths={[ 'react/button-story-with-addon-example.js.mdx', 'vue/button-story-with-addon-example.js.mdx', 'angular/button-story-with-addon-example.ts.mdx', ]} />

This is how you can select the above story:

<CodeSnippets paths={[ 'common/storybook-addons-api-selectstory.js.mdx', ]} />

api.selectInCurrentKind()

Same as selectStory, but accepts a story inside current kind as the only parameter:

<CodeSnippets paths={[ 'common/storybook-addons-api-selectincurrentkind.js.mdx', ]} />

api.setQueryParams()

This method allows you to set query string parameters. You can use that as temporary storage for addons. Here's how you set query params.

<CodeSnippets paths={[ 'common/storybook-addons-api-setqueryparams.js.mdx', ]} />

If you need to remove a query param, use null for that. For an example, let's say we need to remove bbc query param. This is how we do it:

<CodeSnippets paths={[ 'common/storybook-addons-api-disablequeryparams.js.mdx', ]} />

api.getQueryParam()

This method allows you to get a query param set by above API setQueryParams. For example, let's say we need to get the bbc query param. Then this how we do it:

<CodeSnippets paths={[ 'common/storybook-addons-api-getqueryparam.js.mdx', ]} />

api.getUrlState(overrideParams)

This method allows you to get application url state with some changed params. For example, if you want to get a link to a particular story:

<CodeSnippets paths={[ 'common/storybook-addons-api-geturlstate.js.mdx', ]} />

api.on(eventName, fn)

This method allows you to register a handler function which will be called whenever the user navigates between stories.

<CodeSnippets paths={[ 'common/storybook-addons-api-on.js.mdx', ]} />