React Component Library Toolkit

This project skeleton was created to help people get started with creating their own React component library using:

• Rollup
• TypeScript
• ~~Sass~~ (This dependency has been removed, see Using CSS Preprocessors on how to support it)

It also features:

• ~~Storybook to help you create and show off your components~~
• Jest and React Testing Library enabling testing of the components

Read the blog post about why and how this project skeleton was created ▸

Check out this CodeSandbox to see the component library in action ▸

Development

Testing

npm run test

Building

npm run build

Generating New Components

I've included a handy NodeJS util file under util called create-component.js. Instead of copy pasting components to create a new component, you can instead run this command to generate all the files you need to start building out a new component. To use it:

npm run generate YourComponentName

This will generate:

/src
  /YourComponentName
    YourComponentName.tsx
    YourComponentName.test.tsx
    YourComponentName.types.ts
    YourComponentName.css

The default templates for each file can be modified under util/templates.

Don't forget to add the component to your index.ts exports if you want the library to export the component!

Installing Component Library Locally

Let's say you have another project (test-app) on your machine that you want to try installing the component library into without having to first publish the component library. In the test-app directory, you can run:

npm i --save ../react-component-library

which will install the local component library as a dependency in test-app. It'll then appear as a dependency in package.json like:

  ...
  "dependencies": {
    ...
    "react-component-library": "file:../react-component-library",
    ...
  },
  ...

Your components can then be imported and used in that project.

NOTE: After installing the component library locally, you may run into:

Invalid hook call. Hooks can only be called inside of the body of a function component. This could happen for one of the following reasons:

You might have mismatching versions of React and the renderer (such as React DOM)
You might be breaking the Rules of Hooks
You might have more than one copy of React in the same app See for tips about how to debug and fix this problem.

This is the most commonly encountered problem people face when installing the library locally. This is most likely due to the third reason: You might have more than one copy of React in the app.

Normally when a library is published, dev dependencies are excluded. However, when the library is symlinked, all local dev depdendencies are persisted in the libraries node_modules (includes React). Your bundler may see two versions of React, one in the consuming app and one in the symlinked library. The solution is to have the component library use the React version in the consuming app. So from your component library folder, run:

npm link ../test-app/node_modules/react

OR, if you are using Webpack in app you can follow this GitHub comment.

Read more about this issue here.

Publishing

Hosting via NPM

First, make sure you have an NPM account and are logged into NPM using the npm login command.

Then update the name field in package.json to reflect your NPM package name in your private or public NPM registry. Then run:

npm publish

The "prepublishOnly": "npm run build" script in package.json will execute before publish occurs, ensuring the build/ directory and the compiled component library exist.

Hosting via GitHub

I recommend you host the component library using NPM. However, if you don't want to use NPM, you can use GitHub to host it instead.

You'll need to remove build/ from .gitignore, build the component library (npm run build), add, commit and push the contents of build. See this branch for an example.

You can then install your library into other projects by running:

npm i --save git+https://github.com/HarveyD/react-component-library.git#branch-name

OR

npm i --save github:harveyd/react-component-library#branch-name

Usage

Let's say you created a public NPM package called harvey-component-library with the TestComponent component created in this repository.

Stylesheet

First, you'll need to import the index.css CSS file distributed by the package. This should be done at the root of your project (in index.js or App.tsx of your React app) and will look like:

import 'harvey-component-library/build/index.css';

...

Components

Usage of components (after the library installed as a dependency into another project) will look like:

import React from "react";
import { TestComponent } from "harvey-component-library";

const App = () => (
  <div className="app-container">
    <h1>Hello I'm consuming the component library</h1>
    <TestComponent heading={'Some heading'} content={<div>Some content</div>} />
  </div>
);

export default App;

Check out this Code Sandbox for a live example.

Using Component Library CSS Variables

Above we imported index.css into the root of our project. index.css contains a number of CSS variables that can be used across the project that consumes our component library.

In your CSS, you can use the variables defined in variables.css like:

.example-container {
    color: var(--harvey-white);
    background-color: var(--harvey-black);
}

See: https://developer.mozilla.org/en-US/docs/Web/CSS/Using_CSS_custom_properties for more information about CSS Variables.

Additional Help

Dark Mode

The example component TestComponent respects the user's dark mode operating system preferences and renders the component in the appropriate theme.

This is achieved by using the media query: @media (prefers-color-scheme: dark) in combination with CSS variables. The colours that change depending on dark mode preference can be found in src/index.css. Example usage of these variables can be found within src/TestComponent/TestComponent.css.

Read https://developer.mozilla.org/en-US/docs/Web/CSS/@media/prefers-color-scheme for more details.

Using CSS Preprocessors

The Rollup plugin rollup-plugin-postcss supports Sass, Less and Stylus:

• For Sass, install less: yarn add node-sass --dev
• For Stylus, install stylus: yarn add stylus --dev
• For Less, install less: yarn add less --dev

CSS Modules

If you want to use CSS Modules, update postcss in rollup-config.js to:

postcss({
  modules: true
})

Styled Components

If you want to use styled-components, the changes required are a bit more involved. As such, I've created a branch where I've got styled-components working in this component library, check it out here.

Component Code Splitting

Code splitting of your components is not supported by default.

Read this section of my blog post to find out how and why you would enable code splitting of your components. In summary, code splitting enables users to import components in isolation like:

import TestComponent from 'harvey-component-library/build/TestComponent';

This can reduce the bundle size for projects using older (CJS) module formats.

You can check out this branch or this commit to see what changes are neccesary to implement it.

Please note, there's an issue with code splitting and using rollup-plugin-postcss. I recommend using rollup-plugin-sass instead alongside code splitting.

Supporting Image Imports

Add the following library to your component library @rollup/plugin-image:

npm i -D @rollup/plugin-image

Then add it to rollup-config.js:

...
plugins:[
  ...,
  image(),
  ...
]
...

You can then import and render images in your components like:

import logo from "./rollup.png";

export const ImageComponent = () => (
  <div>
    <img src={logo} />
  </div>
);

Supporting JSON Imports

Add the following library to your component library @rollup/plugin-json:

npm i -D @rollup/plugin-json

Then add it to rollup-config.js:

...
plugins:[
  ...,
  json(),
  ...
]
...

You can then import and use JSON as ES6 Modules:

import data from "./some-data.json";

export const JsonDataComponent = () => <div>{data.description}</div>;

Checkout the official Rollup plugin list for additional helpful plugins.