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Version: v2

React Integration

Supports: React v16.7+ • TypeScript 3.7+ • Stencil v2.9.0+

Stencil can generate React component wrappers for your web components. This allows your Stencil components to be used within a React application. The benefits of using Stencil's component wrappers over the standard web components include:

  • Custom events will be handled correctly and correctly propagate through the React render tree
  • Properties and attributes that are not a string or number will be correctly bound to the component

Setup​

Project Structure​

We recommend using a monorepo structure for your component library with component wrappers. Your project workspace should contain your Stencil component library and the library for the generated React component wrappers.

An example project set-up may look similar to:

top-most-directory/
└── packages/
    ├── stencil-library/
    │   ├── stencil.config.js
    │   └── src/components/
    └── react-library/
        └── src/
            ├── components/
            └── index.ts

This guide uses Lerna for the monorepo, but you can use other solutions such as Nx, Turborepo, etc.

To use Lerna with this walk through, globally install Lerna:

npm install --global lerna

Creating a Monorepo​

note

If you already have a monorepo, skip this section.

# From your top-most-directory/, initialize a workspace
lerna init

# install dependencies
npm install

# install typescript and node types
npm install typescript @types/node --save-dev

Creating a Stencil Component Library​

note

If you already have a Stencil component library, skip this section.

From the packages/ directory, run the following commands to create a Stencil component library:

npm init stencil components stencil-library
cd stencil-library
# Install dependencies
npm install

Creating a React Component Library​

note

If you already have a React component library, skip this section.

The first time you want to create the component wrappers, you will need to have a React library package to write to.

Run the following commands from the root directory of your monorepo to create a React component library:

# Create a project
lerna create react-library # fill out the prompts accordingly
cd packages/react-library

# Install core dependencies
npm install react react-dom typescript @types/react --save-dev

Lerna does not ship with a TypeScript configuration. At the root of the workspace, create a tsconfig.json:

{
  "compilerOptions": {
    "module": "commonjs",
    "declaration": true,
    "noImplicitAny": false,
    "removeComments": true,
    "noLib": false,
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "target": "es6",
    "sourceMap": true,
    "lib": ["es6"]
  },
  "exclude": ["node_modules", "**/*.spec.ts", "**/__tests__/**"]
}

In your react-library project, create a project specific tsconfig.json that will extend the root config:

{
  "extends": "../../tsconfig.json",
  "compilerOptions": {
    "outDir": "./dist",
    "lib": ["dom", "es2015"],
    "module": "es2015",
    "moduleResolution": "node",
    "target": "es2015",
    "skipLibCheck": true,
    "jsx": "react",
    "allowSyntheticDefaultImports": true,
    "declarationDir": "./dist/types"
  },
  "include": ["lib"],
  "exclude": ["node_modules"]
}

Update the generated package.json in your react-library, adding the following options to the existing config:

{
-  "main": "lib/react-library.js",
+  "main": "dist/index.js",
+  "module": "dist/index.js",
+  "types": "dist/types/index.d.ts",
  "scripts": {
-    "test": "node ./__tests__/react-library.test.js"
+    "test": "node ./__tests__/react-library.test.js",
+    "build": "npm run tsc",
+    "tsc": "tsc -p . --outDir ./dist"
-  }
+  },
   "files": [
-    "lib"
+    "dist"
   ],
+  "publishConfig": {
+    "access": "public"
+  },
+  "dependencies": {
+    "stencil-library": "*"
+  }
}
note

The stencil-library dependency is how Lerna knows to resolve the internal Stencil library dependency. See Lerna's documentation on package dependency management for more information.

Adding the React Output Target​

Install the @stencil/react-output-target dependency to your Stencil component library package.

# Install dependency
npm install @stencil/react-output-target --save-dev

In your project's stencil.config.ts, add the reactOutputTarget configuration to the outputTargets array:

import { reactOutputTarget } from '@stencil/react-output-target';

export const config: Config = {
  namespace: 'stencil-library',
  outputTargets: [
    // By default, the generated proxy components will
    // leverage the output from the `dist` target, so we
    // need to explicitly define that output alongside the
    // React target
    {
      type: 'dist',
      esmLoaderPath: '../loader',
    },
    reactOutputTarget({
      componentCorePackage: 'stencil-library',
      proxiesFile: '../react-library/lib/components/stencil-generated/index.ts',
    }),
  ],
};
tip

The proxiesFile is the relative path to the file that will be generated with all of the React component wrappers. You will replace the file path to match your project's structure and respective names. You can generate any file name instead of index.ts.

The componentCorePackage should match the name field in your Stencil project's package.json.

See the API section below for details on each of the output target's options.

You can now build your Stencil component library to generate the component wrappers.

# Build the library and wrappers
npm run build

If the build is successful, you’ll see the new generated file in your React component library at the location specified by the proxiesFile argument.

Add the Components to your React Component Library's Entry File​

In order to make the generated files available within your React component library and its consumers, you’ll need to export everything from within your entry file. First, rename react-library.js to index.ts. Then, modify the contents to match the following:

export * from './components/stencil-generated';

Registering Custom Elements​

To register your web components for the lazy-loaded (hydrated) bundle, you'll need to expose a method for registering the underlying Stencil generated custom elements for the React proxy components to leverage. The easiest way to do this is to modify the React library's entry file to re-export the Stencil loader's defineCustomElements() method. In your React library's entry file (packages/react-library/lib/index.ts), add the following:

export * from "./components/stencil-generated";
+ export { defineCustomElements } from "stencil-library/loader";
note

If you are using a monorepo tool (Lerna, Nx, etc.), skip this section.

Before you can successfully build a local version of your React component library, you will need to link the Stencil package to the React package.

From your Stencil project's directory, run the following command:

# Link the working directory
npm link

From your React component library's directory, run the following command:

# Link the package name
npm link name-of-your-stencil-package

The name of your Stencil package should match the name property from the Stencil component library's package.json.

Your component libraries are now linked together. You can make changes in the Stencil component library and run npm run build to propagate the changes to the React component library.

tip

As an alternative to npm link , you can also run npm install with a relative path to your Stencil component library. This strategy, however, will modify your package.json so it is important to make sure you do not commit those changes.

Consumer Usage​

Creating a Consumer React App​

note

If you already have a React app, skip this section.

From the packages/ directory, run the following commands to create a starter React app:

# Create the React app
npm create vite@latest my-app -- --template react-ts
# of if using yarn
yarn create vite my-app --template react-ts

cd ./my-app

# install dependencies
npm install
# or if using yarn
yarn install

You'll also need to link your React component library as a dependency. This step makes it so your React app will be able to correctly resolve imports from your React library. This is easily done by modifying your React app's package.json to include the following:

"dependencies": {
  "react-library": "*"
}

Consuming the React Wrapper Components​

This section covers how developers consuming your React component wrappers will use your package and component wrappers.

Before you can consume your React proxy components, you'll need to build your React component library. From packages/react-library run:

npm run build

To make use of your React component library in your React application, import your components from your React component library in the file where you want to use them.

// App.tsx
import './App.css';
import { MyComponent, defineCustomElements } from 'react-library';

defineCustomElements();

function App() {
  return (
    <div className="App">
      <MyComponent first="Your" last="Name" />
    </div>
  );
}

export default App;

API​

componentCorePackage​

Optional

Default: The components.d.ts file in the Stencil project's package.json types field

Type: string

The name of the Stencil package where components are available for consumers (i.e. the value of the name property in your Stencil component library's package.json). This is used during compilation to write the correct imports for components.

For a starter Stencil project generated by running:

npm init stencil component my-component-lib

The componentCorePackage would be set to:

// stencil.config.ts

export const config: Config = {
  ...,
  outputTargets: [
    reactOutputTarget({
      componentCorePackage: 'my-component-lib',
      // ... additional config options
    })
  ]
}

Which would result in an import path like:

import { defineCustomElement as defineMyComponent } from 'my-component-lib/components/my-component.js';
note

Although this field is optional, it is highly recommended that it always be defined to avoid potential issues with paths not being generated correctly when combining other API arguments.

customElementsDir​

Optional

Default: 'dist/components'

Type: string

If includeImportCustomElements is true, this option can be used to specify the directory where the generated custom elements live. This value only needs to be set if the dir field on the dist-custom-elements output target was set to something other than the default directory.

excludeComponents​

Optional

Default: []

Type: string[]

This lets you specify component tag names for which you don't want to generate React wrapper components. This is useful if you need to write framework-specific versions of components. For instance, in Ionic Framework, this is used for routing components - like tabs - so that Ionic Framework can integrate better with React Router.

includeDefineCustomElements​

Optional

Default: true

Type: boolean

If true, all Web Components will automatically be registered with the Custom Elements Registry. This can only be used when lazy loading Web Components and will not work when includeImportCustomElements is true.

includeImportCustomElements​

Optional

Default: undefined

Type: boolean

If true, the output target will import the custom element instance and register it with the Custom Elements Registry when the component is imported inside of a user's app. This can only be used with the Custom Elements output and will not work with lazy loaded components.

includePolyfills​

Optional

Default: true

Type: boolean

If true, polyfills will automatically be imported and the applyPolyfills function will be called in your proxies file. This can only be used when lazy loading Web Components and will not work when includeImportCustomElements is enabled.

loaderDir​

Optional

Default: /dist/loader

Type: string

The path to where the defineCustomElements helper method exists within the built project. This option is only used when includeDefineCustomElements is enabled.

proxiesFile​

Required

Type: string

This parameter allows you to name the file that contains all the component wrapper definitions produced during the compilation process. This is the first file you should import in your React project.

FAQ's​

Do I have to use the dist output target?​

No! By default, this output target will look to use the dist output, but the output from dist-custom-elements can be used alternatively.

To do so, simply set the includeImportCustomElements option in the output target's config and ensure the custom elements output target is added to the Stencil config's output target array:

// stencil.config.ts

export const config: Config = {
  ...,
  outputTargets: [
    // Needs to be included
    {
      type: 'dist-custom-elements'
    },
    reactOutputTarget({
      componentCorePackage: 'component-library',
      proxiesFile: '{path to your proxy file}',
      // This is what tells the target to use the custom elements output
      includeImportCustomElements: true
    })
  ]
}

Now, all generated imports will point to the default directory for the custom elements output. If you specified a different directory using the dir property for dist-custom-elements, you need to also specify that directory for the React output target. See the API section for more information.

In addition, all the Web Components will be automatically defined as the generated component modules are bootstrapped.

TypeError: Cannot read properties of undefined (reading 'isProxied')​

If you encounter this error when running the React application consuming your proxy components, you can set the experimentalImportInjection flag on the Stencil config's extras object. Once set, this will require you to rebuild the Stencil component library and the React component library.

What is the best format to write event names?​

Event names shouldn’t include special characters when initially written in Stencil. Try to lean on using camelCased event names for interoperability between frameworks.

How do I add IE11 or Edge support?​

If you want your custom elements to work on older browsers, you should call the applyPolyfills() function before defineCustomCustomElements(). applyPolyfills() returns a Promise, so you could call it like this:

import { applyPolyfills, defineCustomElements } from 'test-components/loader';

applyPolyfills().then(() => {
  defineCustomElements();
});

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