How to set up a Node and TypeScript project with Vitest

What this stack gives you

TypeScript adds static types to JavaScript, catching errors before runtime. Node.js runs the code. Vitest is a fast, modern test runner with a Jest-compatible API and first-class TypeScript and ESM support. Together they give a quick, type-safe development loop.

Prerequisites

• Node.js 18 or later
• A terminal

Steps

1. Initialize the project

mkdir stringutils && cd stringutils
npm init -y

2. Install TypeScript and Vitest

npm install -D typescript vitest

3. Configure the TypeScript compiler

Create tsconfig.json with sensible strict settings.

{
  "compilerOptions": {
    "target": "ES2022",
    "module": "ESNext",
    "moduleResolution": "Bundler",
    "strict": true
  }
}

4. Write code to test

// src/slug.ts
export function slugify(input: string): string {
  return input.trim().toLowerCase().replace(/\s+/g, "-");
}

5. Write a Vitest test

Vitest discovers files ending in .test.ts.

// src/slug.test.ts
import { describe, it, expect } from "vitest";
import { slugify } from "./slug";

describe("slugify", () => {
  it("lowercases and hyphenates", () => {
    expect(slugify("Hello World")).toBe("hello-world");
  });
});

6. Run tests and watch mode

Add scripts to package.json and run them.

{ "scripts": { "test": "vitest run", "test:watch": "vitest" } }

npm test

Verification

Run npm test and confirm the test passes. Change the expected string to a wrong value and confirm Vitest reports the diff, then fix it. Run npm run test:watch and confirm it reruns on save.

Next Steps

Add coverage with vitest run --coverage, set up ESLint and Prettier, add type checking with tsc --noEmit, and run tests in continuous integration.