In this lesson we look at how to create a React Component package using TypeScript.

Creating a React Package is very similar to creating any other TypeScript Node package and we demonstrate that here.

Here we have a simple bare bones package.json for a node module which have named 'fancy'. cat package.json

{
  "name": "fancy",
  "version": "0.0.0",
  "license": "MIT",
  "repository": {
    "type": "git",
    "url": "https://github.com/basarat/typescript-react.git"
  },
  "scripts": {}
}

We start off by installing typescript / react and the types for react as dev dependencies.

npm install typescript react @types/react -D

• We add these only as dev dependencies as we want people that will use our package to bring in their own versions for these libraries.

• Next we create a simple tsconfig.json file.

• Within the file we specify the compilerOptions for sourceMap / target / jsx / declaration and most importantly the output directory for the compiled JavaScript and declaration files using outDir.

• We also specify that our source TypeScript files will be in the src folder.

{
  "compilerOptions": {
    "sourceMap": true,
    "target": "es5",
    "jsx": "react",
    "declaration": true,
    "outDir": "lib"
  },
  "include": [
    "src"
  ]
}

• Next we simply create our root src/index.tsx file.
• Within the file we bring in React.
• Next we export a simple Fancy component that takes a text prop and renders it into an h1 tag.

import * as React from 'react';

export const Fancy: React.SFC<{ text: string }>
  = (props) => <h1>{props.text}</h1>;

• We wrap up our module by making a final set of changes in package.json
• We add a hint for our users that they need to provide their own version of react by adding to our peerDependencies.

  "peerDependencies": {
    "react": ">=16.0.0"
  },

• We setup package.json with the path to our output js files along with types for the output .d.ts TypeScript declaration files which in our case is the outDir we specified in our tsconfig.json

"main": "lib",
"types": "lib",

• We also setup a build script which simply invokes tsc on our tsconfig.json
• Add a start script that runs build in watch mode for live development.

"build": "tsc -p .",
"start": "npm run build -- -w"

• Now lets go ahead and run build once on the console to compile our project.

npm run build

• At this point if you wanted you could run npm publish to push this library to NPM, but we will just use it locally by running npm link.

npm link

• Now lets jump back to our good old hello world react application and use this fancy package.

cd ../use

• If we had published our package to npm we could use it with npm install fancy but since we only linked it locally we can bring it in by running npm link fancy. This npm link workflow is also a good tool to be aware of for local testing of packages before deploying them to npm.

npm link fancy

alm -o && Run the demo

• We start with a simple basic TypeScript hello world react app.
• We now import the Fancy component into our application. Ofcourse since the Fancy package was written with TypeScript we get nice autocomplete, error checking and all the other benefits we demonstarted in the first lesson.

import { Fancy } from 'fancy';

ReactDOM.render(
  <Fancy text="Hello world"/>,
  document.getElementById('root')
);

• As you can see our fancy component works as expected.