Node + TypeScript + Jest (Oct 2024)

Intro

Recently I wanted to do some quick coding but spent more time getting a project setup with what I consider the absolute basics to code: type-checking and unit tests.

Tooling

Current state-of-the-art / flavor-of-the-month tooling is:

• mise for managing tooling and node versions
• Node v22: mise install node@22 && mise use --global node@22
• pnpm instead of npm
  • mise install pnpm && mise use --global pnpm

Intro: decisions

Setting up a starter project template with:

1. Node without-DOM libraries
2. TypeScript for sanity
3. Jest for unit testing

Structure conventions:

• src/ all source files file.ts and test files file.test.ts within
• dist/ output *.js files within. Start file is dist/index.js

npm and git

pnpm init
git init
mkdir dist src # dist=output, src=all files in here

Edit .gitignore

node_modules
dist
coverage

Install

Install basics, TypeScript, and Jest:

pnpm install --save-dev nodemon rimraf \
  typescript ts-node @types/node \
  jest ts-jest @types/jest

Scripts

Edit package.json

{
  "main": "dist/index.js",
  "scripts": {
    "build": "rimraf dist/ && tsc",
    "start": "node dist/index.js",
    "dev": "nodemon --watch 'src/**' --ext 'ts,json' --ignore 'src/**/*.test.ts' --exec 'ts-node --files --compilerHost --transpilerOnly src/index.ts'",
    "test": "jest",
  }
}

Mostly self explanatory: dev for development. build and start for production. test for testing. The nodemon mouthful in dev is optimizing for speed.

TypeScript configuration

Initialize: pnpm tsc --init Edit tsconfig.json to configure it to work with Node and our Structure Conventions

{
  "include": ["src/**/*.ts"],
  "exclude": ["src/**/*.test.ts"],
  "compilerOptions": {
    "target": "es2022",
    "module": "Node16",
    "rootDir": "./src",
    "outDir": "./dist",
    "lib": ["es2023"],
  }
}

These choices are:

• Look for source in src but don't output unit test files.
• "target": "es2022" , a target well supported by Node v18+
• "module": "Node16", to use the modern import and keeping Node compatibility
• Sticking with the Structure Conventions of source in src/ and output in dist/
• "lib": ["es2023"], to exclude the DOM libraries like document
• tsconfig documentation

Jest configuration

Initialize: pnpm jest --init

Answer the init questionnaire:

• Typescript? Yes
• Test Environment? Node
• Coverage? Yes
• Provider? v8
• Auto clear mocks? Yes

Edit jest.config.ts for TypeScript compatability "preset": "ts-jest"

HAPPY HACKING!!!

TODO

• Prettier for formatting
• ESLint for linting
• husky for pre-commit hooks and thus enforce formatting and linting