On a command line with npm in your path, run the following command:

npm install –g typescript

The npm option –g tells npm to install the TypeScript compiler globally, so it's available to every Node.js application you write. Once you run it, npm downloads and installs the TypeScript compiler binary for your platform.

Once you run this command to install the compiler, you'll have the TypeScript compiler tsc available on the command line. Compiling a file with tsc is as easy as writing the source code and saving in a file that ends in .ts extension, and running tsc on it. For example, given the following TypeScript saved in the file hello.ts:

function greeter(person: string) {
  return "Hello, " + person...