Storybook for Web components & Webpack

Storybook for Web components & Webpack is a framework that makes it easy to develop and test UI components in isolation for applications using Web components built with Webpack.

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:

npm create storybook@latest

More on getting started with Storybook.

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:

npx storybook@latest upgrade

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:

npm install --save-dev @storybook/web-components-webpack5

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

npx storybook@latest add @storybook/addon-webpack5-compiler-swc

or

npx storybook@latest add @storybook/addon-webpack5-compiler-babel

More details can be found in the Webpack builder docs.

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

import { StorybookConfig } from '@storybook/web-components-webpack5';
 
const config: StorybookConfig = {
  // ...
  framework: '@storybook/web-components-webpack5', // 👈 Add this
};
 
export default config;

Hot Module Reloading (HMR)

Web components are registered on a global registry, which only accepts a given name/class once. That can lead to errors when using classical HMR. While there are ideas for achieving HMR with a static registry, there has yet to be a proven solution. Therefore, the best approach, for now, is to do full-page reloads while developing. You can ensure that page reloads happen quickly by defining your stories as specific states of components (which we recommend regardless).

Set up ES6/7 dependencies

By default, Storybook only works with precompiled ES5 code. Because most Web Components and their libs are distributed as ES2017, you must mark those packages as "needs transpilation" manually.

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

import type { StorybookConfig } from '@storybook/web-components-webpack5';
 
const config: StorybookConfig = {
  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;
  },
};
 
export default 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

API

Options

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

import type { StorybookConfig } from '@storybook/web-components-webpack5';
 
const config: StorybookConfig = {
  framework: {
    name: '@storybook/web-components-webpack5',
    options: {
      // ...
    },
  },
};
 
export default config;

The available options are:

builder

Type: Record<string, any>

Configure options for the framework's builder. For this framework, available options can be found in the Webpack builder docs.

Troubleshooting

Error while developing with HMR

While developing a component, you might encounter this error:

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. For more information, see the limitations of HMR with web components.