NodeJS Console App with TypeScript, linting and testing

Let's dive right into it, lean and mean.

The base project 🚀

1) Create your project folder and enter it

2) Run npm init -y

3) Install the following packages:

yarn add typescript ts-node ts-node-dev @types/node -D

4) Add the tsconfig.json file in the root and this as content:

{
  "compilerOptions": {
    "target": "es6",
    "module": "commonjs",
    "outDir": "dist",
    "rootDir": "src",
    "strict": true,
    "sourceMap": true,
    "moduleResolution": "node",
    "esModuleInterop": true
  },
  "include": ["src/**/*.ts"],
  "exclude": ["node_modules"]
}

5) Edit package.json to add some useful scripts

"scripts": {
  "build": "tsc",
  "dev": "ts-node-dev --respawn ./src/index.ts",
  "start": "ts-node ./src/index.ts"
},

6) Add some starter code

Create src/getGreeting.ts with:

export function getGreeting(name: string): string {
  return `Hello, ${name}!`;
}

Create src/index.ts with:

import { getGreeting } from "./getGreeting";

const greeting = getGreeting("John");
console.log(greeting);

7) Run the project

• Use yarn build to build the project and see the output at /dist
• Use yarn dev to start your application in dev mode, which will hot-reload upon changes to the code
• Use yarn start to start your application without hot-reload

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Additional capabilities 📦

Linting 🔎

Install the packages:

yarn add eslint typescript @typescript-eslint/parser @typescript-eslint/eslint-plugin -D

Create .eslintrc.js in the root with:

module.exports = {
  root: true,
  parser: "@typescript-eslint/parser",
  plugins: ["@typescript-eslint"],
  extends: ["eslint:recommended", "plugin:@typescript-eslint/recommended"],
};

Create .eslintignore in the root with:

node_modules
dist
.eslintrc.js

Add/modify the scripts in package.json:

"build": "eslint . --ext .ts && tsc",
"lint": "eslint . --ext .ts"

Run the linter with yarn lint. The "build" command now runs the linter as well.

Testing 🧪

Install the packages:

yarn add jest ts-jest @types/jest -D

Create jest.config.ts in the root with:

import type { Config } from "jest";

const config: Config = {
  verbose: true,
  preset: "ts-jest",
  testEnvironment: "node",
};

export default config;

Create src/getGreeting.spec.ts with:

import { describe, expect, it } from "@jest/globals";
import { getGreeting } from "./getGreeting";

describe("getGreeting", () => {
  it("should return Hello, John!", () => {
    expect(getGreeting("John")).toEqual("Hello, John!");
  });
});

Add the script in package.json:

"test": "jest"

Modify the exclude clause in tsconfig.json to read:

"exclude": ["node_modules", "src/**/*.spec.ts"]

Run your tests with yarn test.

For a better experience, make sure you have the Jest extension, which will show a side-bar in VS Code, will autorun tests as they are created or modified, and will allow you to right-click to run or debug a test.

Debugging 🪲

Create .vscode/launch.json with:

{
  // Use IntelliSense to learn about possible attributes.
  // Hover to view descriptions of existing attributes.
  // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
  "version": "0.2.0",
  "configurations": [
    {
      "type": "node",
      "request": "launch",
      "name": "Launch Program",
      "skipFiles": ["<node_internals>/**"],
      "args": ["${workspaceFolder}/src/index.ts"],
      "runtimeArgs": ["--nolazy", "-r", "ts-node/register"],
      "sourceMaps": true,
      "cwd": "${workspaceFolder}"
    }
  ]
}

Press F5 or go to the "Run and Debug" tab and hit play to start debugging.

Other features ✨

Refer to my older post for instructions on how to add support for environment variables, API access and asycn and await.

Bonus 🎁

Download the finished starter project from https://github.com/phillippelevidad/nodejs-typescript-starter.

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References 📖

• Jest With Typescript
• How to add eslint
• Building a NodeJS app with TypeScript
• How to use NodeJS with TypeScript
• Debugging TypeScript in VS Code without compiling, using ts-node