Typescript for Node

How to get started on a Typescript CLI project using yarn for package management and nvm for managing node versions.

Set up the overall environment

nvm install lts/*
npm install -g strip-json-comments-cli
npm install -g yarn

Set up the project directory. I use ~/src/<project>

mkdir <applicationname>
cd <applicationname>
node --version > .nvmrc
yarn init -y

Example package.json for the typescript-nodejs-example application.

{
  "name": "typescript-nodejs-example",
  "version": "0.1.0",
  "main": "index.js",
  "author": "Mark C Allen <mark@markcallen.com>",
  "license": "MIT"
}

Add typescript

yarn add -D typescript @types/node tsx rimraf

Create a tsconfig.json

# create a tsconfig.json file
npx tsc --init --rootDir src --outDir dist \
--esModuleInterop --target esnext --module nodenext \
--verbatimModuleSyntax false --allowJs true --noImplicitAny true

# remove the comments and whitespace so that it's readable
cat tsconfig.json | strip-json-comments --no-whitespace | \
jq -r . > tsconfig.pretty.json && mv tsconfig.pretty.json tsconfig.json

# add in node as a type
npx json -I -f tsconfig.json -e 'this.compilerOptions.types=["node"]'

The resulting tsconfig.json is like this:

{
  "compilerOptions": {
    "rootDir": "src",
    "outDir": "dist",
    "module": "nodenext",
    "target": "esnext",
    "types": [
      "node"
    ],
    "sourceMap": true,
    "declaration": true,
    "declarationMap": true,
    "noUncheckedIndexedAccess": true,
    "exactOptionalPropertyTypes": true,
    "strict": true,
    "jsx": "react-jsx",
    "verbatimModuleSyntax": true,
    "isolatedModules": true,
    "noUncheckedSideEffectImports": true,
    "moduleDetection": "force",
    "skipLibCheck": true,
    "esModuleInterop": true,
    "resolveJsonModule": true,
    "allowJs": true,
    "noImplicitAny": true
  }
}

Let's create a Hello World script and test

mkdir src

Add the following to src/index.ts

console.log('hello world!!');

// Keep the process alive until Ctrl-C
process.stdin.resume();

// Optional: Handle graceful shutdown on Ctrl-C
process.on('SIGINT', () => {
  console.log('\nGoodbye!');
  process.exit();
});

Add a helper script, build.

npm pkg set "scripts.build"="rimraf ./dist && tsc"
yarn build

Now, let's add a start script

npm pkg set "scripts.start"="node dist/index.js"

Running yarn start will return. Press ctrl-c to exit.

yarn run v1.22.22
$ node dist/index.js
hello world!!

^C
Goodbye!

Adding Development

Since we don't want to compile this each time, let's add a dev script to use tsx to compile and run the script in one command.

npm pkg set "scripts.dev"="tsx src/index.js"

Now, we can run and again press ctrl-c to exit.

yarn dev

yarn run v1.22.22
$ tsx src/index.js
hello world!!
^C
Goodbye!

Setup Git

Let's add everything to git

git init

cat << EOF > .gitignore
.env
yarn-error.log
dist/
node_modules/
EOF

git add .
git commit -m "First checkin" -a

We now have a project set up for TypeScript to use Node.js.

I've shared this project on github as an example: https://github.com/markcallen/typescript-nodejs-example