storybook/docs/get-started/web-components-webpack5.md

---
title: Storybook for Web components & Webpack
---

export const SUPPORTED_RENDERER = 'web-components';

Storybook for Web components & Webpack is a [framework](../contribute/framework.md) that makes it easy to develop and test UI components in isolation for applications using [Web components](https://www.webcomponents.org/introduction) built with [Webpack](https://webpack.js.org/).

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<Callout variant="info">

Storybook for Web components & Webpack is only supported in [Web components](?renderer=web-components) projects.

</Callout>

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## Requirements

- Webpack ≥ 5.0
- Storybook ≥ 8.0

## Getting started

### In a project without Storybook

Follow the prompts after running this command in your Web components project's root directory:

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<CodeSnippets
  paths={[
   'common/init-command.npx.js.mdx',
   'common/init-command.yarn.js.mdx',
   'common/init-command.pnpm.js.mdx',
  ]}
/>

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[More on getting started with Storybook.](./install.md)

### In a project with Storybook

This framework is designed to work with Storybook 7+. If you’re not already using v7, upgrade with this command:

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<CodeSnippets
  paths={[
    'common/storybook-upgrade.npm.js.mdx',
    'common/storybook-upgrade.pnpm.js.mdx',
    'common/storybook-upgrade.yarn.js.mdx'
  ]}
/>

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#### Automatic migration

When running the `upgrade` command above, you should get a prompt asking you to migrate to `@storybook/web-components-webpack5`, which should handle everything for you. In case that auto-migration does not work for your project, refer to the manual migration below.

#### Manual migration

First, install the framework:

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<CodeSnippets
  paths={[
    'web-components/web-components-webpack5-install.npm.js.mdx',
    'web-components/web-components-webpack5-install.pnpm.js.mdx',
    'web-components/web-components-webpack5-install.yarn.js.mdx'
  ]}
/>

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Next, install and register your appropriate compiler addon, depending on whether you're using SWC (recommended) or Babel:

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<CodeSnippets
  paths={[
    'common/storybook-addon-compiler-swc-auto-install.npm.js.mdx',
    'common/storybook-addon-compiler-swc-auto-install.pnpm.js.mdx',
    'common/storybook-addon-compiler-swc-auto-install.yarn.js.mdx',
  ]}
/>

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or

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<CodeSnippets
  paths={[
    'common/storybook-addon-compiler-babel-auto-install.npm.js.mdx',
    'common/storybook-addon-compiler-babel-auto-install.pnpm.js.mdx',
    'common/storybook-addon-compiler-babel-auto-install.yarn.js.mdx',
  ]}
/>

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More details can be found in the [Webpack builder docs](../builders/webpack.md#compiler-support).

Finally, update your `.storybook/main.js|ts` to change the framework property:

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<CodeSnippets
  paths={[
    'web-components/web-components-webpack5-add-framework.js.mdx',
    'web-components/web-components-webpack5-add-framework.ts.mdx'
  ]}
/>

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## Hot Module Reloading (HMR)

Web components are registered on global registry, which only accepts a given name/class once. That can lead to errors when using classical HMR. While there are ideas on how to achieve HMR with a static registry, there is no proven solution yet. Therefore, the best approach for now is to do full page reloads while developing. You can ensure those page reloads happen quickly by defining your stories as specific states of components (which we would recommend regardless).

## Set up es6/7 dependencies

By default, Storybook only works with precompiled ES5 code. Because most web components themselves and their libs are distributed as ES2017, you will need to manually mark those packages as "needs transpilation".

For example, if you have a library called `my-library` which is in ES2017, then you can configure your project like so:

```js
// .storybook/main.js

export default {
  webpackFinal: async (config) => {
    // Find web-components rule for extra transpilation
    const webComponentsRule = config.module.rules.find(
      (rule) => rule.use && rule.use.options && rule.use.options.babelrc === false
    );
    // Add your own `my-library`
    webComponentsRule.test.push(new RegExp(`node_modules(\\/|\\\\)my-library(.*)\\.js$`));

    return config;
  },
};
```

By default, the following folders are transpiled:

- `src/*.js`
- `packages/*/src/*.js`
- `node_modules/lit-html/*.js`
- `node_modules/lit-element/*.js`
- `node_modules/@open-wc/*.js`
- `node_modules/@polymer/*.js`
- `node_modules/@vaadin/*.js`

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Note that the `src` folder is also included. This provides some extra configuration to allow for `import.meta` and some other features.

If you use a folder for your components/stories other than `src`, you will need to use the configuration example above to have it properly transpiled.

</Callout>

## API

### Options

You can pass an options object for additional configuration if needed:

```js
// .storybook/main.js
import * as path from 'path';

export default {
  // ...
  framework: {
    name: '@storybook/web-components-webpack5',
    options: {
      // ...
    },
  },
};
```

The available options are:

#### `builder`

Type: `Record<string, any>`

Configure options for the [framework's builder](../api/main-config-framework.md#optionsbuilder). For this framework, available options can be found in the [Webpack builder docs](../builders/webpack.md).

## Troubleshooting

### Error while developing with HMR

While developing a component, you might encounter this error:

```sh
Failed to execute 'define' on 'CustomElementRegistry': the name "..." has already been used with this registry
```

This error occurs because the component is already registered in the global registry. See the [limitations of HMR with web components](#hot-module-reloading-hmr) for more information.

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