---
title: 'Toolbars & globals'
---

Storybook ships with toolbar items to control the [viewport](./viewport.md) and [background](./backgrounds.md) the story renders in. You can also create your own toolbar items which control special “globals” which you can then read to create [decorators](../writing-stories/decorators.md) to control story rendering.

### Globals

Globals in Storybook represent “global” (as in not story-specific) inputs to the rendering of the story. As they aren’t specific to the story, they aren’t passed in the `args` argument to the story function (although they are accessible as `context.globals`), but typically you use them in decorators which apply to all stories.

When the globals change, the story re-renders and the decorators rerun with the new values. The easiest way to change globals is to create a toolbar item for them. 

Let’s see how.

### Global types and the toolbar annotation

Storybook has a simple, declarative syntax for configuring toolbar menus. In your [`.storybook/preview.js`](../configure/overview.md#configure-story-rendering), you can add your own toolbars by creating `globalTypes` with a `toolbar` annotation: 

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<CodeSnippets
  paths={[
    'common/storybook-preview-configure-globaltypes.js.mdx',
  ]}
/>

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<div class="aside">

As globals are *global* you can *only* set `globalTypes` in [`.storybook/preview.js`](../configure/overview.md#configure-story-rendering).

</div>

When you start your Storybook, you should see a new dropdown in your toolbar with options `light` and `dark`.

### Create a decorator

We have a `global` defined, let's wire it up! We can consume our new `theme` global in a decorator using the `context.globals.theme` value.

For example, suppose you are using `styled-components`. You can add a theme provider decorator to your [`.storybook/preview.js`](../configure/overview.md#configure-story-rendering) config:

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<CodeSnippets
  paths={[
    'common/storybook-preview-use-global-type.js.mdx',
  ]}
/>

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### Advanced usage

So far we've managed to create and consume a global inside Storybook. 

Now let's take a look at a more complex example. Let's suppose we wanted to implement a new global called __locale__ for internationalization, which shows a flag on the right side of the toolbar. 

In your [`.storybook/preview.js`](../configure/overview.md#configure-story-rendering), add the following:

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<CodeSnippets
  paths={[
    'common/storybook-preview-locales-globaltype.js.mdx',
  ]}
/>

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By adding the the configuration element `right`, the text will displayed on the right side in the toolbar menu, once you connect it to a decorator.

Here's a list of the configuration options available.

| MenuItem      | Type          | Description                                                  | Required |
| ------------- |:-------------:|:------------------------------------------------------------:|:--------:|
| **value**     | String        |The string value of the menu that gets set in the globals     |Yes       |
| **title**     | String        |The main text of the title                                    |Yes       |
| **left**      | String        |A string that gets shown in left side of the menu             |No        |
| **right**     | String        |A string that gets shown in right side of the menu            |No        |
| **icon**      | String        |An icon that gets shown in the toolbar if this item is selected|No        |

### Consuming globals from within a story

We recommend consuming globals from within a decorator and define a global setting for all stories. 

But we're aware that sometimes it's more useful to use toolbar options in a per-story basis.

Using the example above, you can modify any story to retrieve the __Locale__ `global` from the story context:

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<CodeSnippets
  paths={[
    'common/my-component-story-use-globaltype.js.mdx',
  ]}
/>

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<div class="aside">

In Storybook 6.0, if you set the global option `passArgsFirst: false` for backwards compatibility, the story context is passed as the second argument:

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<CodeSnippets
  paths={[
    'common/my-component-story-use-globaltype-backwards-compat.js.mdx',
  ]}
/>

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</div>



### Consuming globals from within an addon

If you're working on a Storybook addon and you need to retrieve globals. You can do so, The `@storybook/api` package provides a hook for this scenario, you can use the `useGlobals()` hook to retrieve any globals you want. 

Using the ThemeProvider example above, you could expand it to display which current theme is being shown inside a panel like so:

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<CodeSnippets
  paths={[
    'common/addon-consume-globaltype.js.mdx',
  ]}
/>

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