TypeScript Get Started

Installing TypeScript

TypeScript is distributed as an npm package. Assuming you already have Node.js and npm installed, you can add TypeScript to a project as a development dependency, or install it globally so the tsc command is available anywhere on your machine.

# Install locally in a project (recommended)
npm install --save-dev typescript

# Or install globally
npm install -g typescript

# Check the installed version
npx tsc --version

Compiling your first file

Create a file named hello.ts with a small piece of typed code, then run the TypeScript compiler against it. The compiler produces a hello.js file containing plain JavaScript, which you can then run with Node.

// hello.ts
function greet(name: string): string {
  return `Hello, ${name}!`;
}

console.log(greet("World"));

# Compile hello.ts into hello.js
npx tsc hello.ts

# Run the compiled JavaScript
node hello.js
// Output: Hello, World!

The tsconfig.json file

Real projects almost always use a tsconfig.json file to configure how the compiler behaves - which JavaScript version to target, how strict the type checking should be, where to put compiled files, and which files to include. Running `tsc --init` generates a starter file with helpful comments.

• target: which version of JavaScript to compile down to (e.g. es2016, esnext).
• strict: turns on the full set of strict type-checking options - highly recommended.
• outDir: the folder where compiled .js files are written.
• rootDir: the folder containing your source .ts files.
• include / exclude: which files or folders the compiler should process.

{
  "compilerOptions": {
    "target": "es2016",
    "module": "commonjs",
    "strict": true,
    "outDir": "./dist",
    "rootDir": "./src"
  },
  "include": ["src/**/*"]
}