Storybook is awesome for building components

I frequently use Storybook and styled components / Emotion when building component libraries. The ability to apply a consistent theme to all components is very powerful but it requires wrapping your components in a ThemeProvider.

Thankfully, there is a straight-forward way to apply a consistent theme object to all of our components in Storybook by using a Storybook Decorator.

Create a theme decorator

We will start by creating a new decorator. In my current projects, this decorator lives in the .storybook folder.

// themeDecorator.js
import React from "react"
import { ThemeProvider, theme } from "./pathToThemeProvider"

const ThemeDecorator = storyFn => (
  <ThemeProvider theme={theme}>{storyFn()}</ThemeProvider>
)

export default ThemeDecorator

Here we include our custom theme provider and define a component that receives a storyFn as a prop. This storyFn is where the Storybook content will be rendered. We wrap the Storybook content in our provider and export our decorator.

Next, in our project's .storybook/config.js, we need to specify that Storybook should use this decorator for all stories.

Use the theme decorator in Storybook config

We'll start by importing our newly created decorator and make sure that we're using the addDecorator method from Storybook.

import { configure, addDecorator } from "@storybook/react"
import themeDecorator from "./themeDecorator"

Next, we'll want to call the following to apply our decorator.

addDecorator(themeDecorator);

Storybook should now be wrapping all stories with a custom decorator. While this article is specifically about CSS-in-JS themes, this strategy works with other types Providers / Wrapper components as well (like Redux).