Simple Nodejs and TypeScript Project Example

Quick Start

mkdir my-project
cd my-project
npm init -y
npm install typescript --save-dev
npm install rimraf --save-dev
touch tsconfig.json
touch index.ts

// tsconfig.json
{
 "compilerOptions": {
    "outDir": "./out",
    "rootDir": "./",
    "sourceMap": true,
    "moduleResolution": "node",
    "target": "es5"
  }
}

// package.json
...
"scripts": {
  "start": "node out/index.js",
  "prestart": "rimraf out && npm run build",
  "build": "./node_modules/typescript/bin/tsc"
},
...

// index.ts
console.log('Main entry point');

npm run start

Initial Setup

First, create the project directory and intialize the Nodejs project.

mkdir my-project
npm init -y

Running npm init -y will create a package.json file in the my-project directory with default values populated. You can omit the -y and run npm init on its own if you’d like to set specific values at creation time, but they can always be changed later.

Install and Configure TypeScript

In the project root (where package.json is) we will run the npm command to install TypeScript. We want to save TypeScript to our package.json devDependencies object, so we’ll include --save-dev in the install command. For now, TypeScript is only needed during development, our “build” files will be JavaScript. We’ll also install the rimraf package, which is a small utility for cleanly removing files or directories.

npm install typescript --save-dev
npm install rimraf --save-dev

Next, we’ll create a tsconfig.json file in the root directory. This file contains all of the configuration settings for TypeScript. Here we will create a simple version of this file by hand. While still in the project root directory:

touch tsconfig.json

And add the following JSON:

{
  "compilerOptions": {
      "outDir": "./out",
      "rootDir": "./",
      "sourceMap": true,
      "moduleResolution": "node",
      "target": "es5"
  }
}

An important thing to note here is the "outDir": "./out", which is where the transpiled JavaScript files will go after we run npm run start

You can have the TypeScript compiler create a more complete version of tsconfig.json for you via tsc --init (if you have TypeScript installed globally) or ./node_modules/typescript/bin/tsc --init from project root.

Compiling and Running

Next we’ll update our package.json file. Add (or update) the following script commands in the scripts block:

"start": "node out/index.js",
"prestart": "rimraf out && npm run build",
"build": "./node_modules/typescript/bin/tsc"

The prestart command will excute each time you run npm run start. In our case, it removes the old out directory and runs the build command.

Before we can run npm run start we’ll need an index.ts file since we specified index.js as our main entry point in the package.json.

// index.ts 
console.log('Main entry point');

Now we can run npm run start. “Main entry point” should be printed to the console and the out directory should be created in the project root containing an the index.js file.