Create a new node js project in typescript (for beginners)

Rajat Srivastava — Sun, 22 Nov 2020 14:51:11 +0000

I used to work on traditional plain javascript code while working on node js. It caused a lot of problems as

Forget how to use the methods, classes or objects that we built into a module long time ago
When a project becomes larger, bugs mostly comes from a minor mistake which typescript helps eliminating

So, I learned how to setup typescript project from scratch

Create a node project using npm

PROJECT_NAME = <project name>
mkdir $PROJECT_NAME && cd $PROJECT_NAME
npm init -y

Install typescript dependencies

npm i --save-dev typescript ts-node nodemon

typescript is for typescript language itself and compiling tool
ts-node is used to run typescript without compiling
nodemon is used to run/restart node automatically when files changed

Initialize tsconfig.json

npx tsc --init

This creates a tsconfig.json in your project folder. This controls the strictness/settings in typescript files

Adjust tsconfig [optional]

Some basic settings in tsconfig.json that are recommended are

{
  "compilerOptions": {
    "target": "es6",
    "module": "commonjs",
    "declaration": true,
    "sourceMap": true,
    "outDir": "dist",
    "rootDir": "./",
    "strict": true,
    "esModuleInterop": true
  }
}

setting target as es6 helps to support es6 code
setting declaration true generates corresponding '.d.ts' file
setting sourceMap true generates corresponding '.map' file
outDir redirects output structure to the directory
rootDir specifies the root directory of input files
setting strict true enables all strict type-checking options

Add program for testing

echo "console.log('Hello typescript !')" > index.ts

Add scripts to package.json

{
  "main": "dist/index.js",
  "types": "dist/index.d.ts",
  "scripts": {
    "start": "ts-node index.ts",
    "build": "tsc"
  },
}

execute npm run start to start application without compile
execute npm run build then node dist/index.js to compile and run applcation as javascript