ts-node/README.md

# ![TypeScript Node](logo.svg)

[![NPM version][npm-image]][npm-url]
[![NPM downloads][downloads-image]][downloads-url]
[![Build status][travis-image]][travis-url]
[![Test coverage][coveralls-image]][coveralls-url]

> TypeScript execution and REPL for node.js, with source map support. **Works with `typescript@>=2.0`**.

**Tip:** `ts-node` differs slightly from `tsc`. It will not load files from `tsconfig.json` by default. Instead, `ts-node` starts from the input file and discovers the rest of the project tree through imports and references.

## Installation

```sh
# Locally in your project
npm install -D ts-node
npm install -D typescript

# Or globally (not recommended)
npm install -g ts-node
npm install -g typescript
```

**Tip:** Installing modules locally allows you to control and share the versions through `package.json`.

## Usage

```sh
# Execute a script as `node` + `tsc`.
ts-node script.ts

# Starts a TypeScript REPL.
ts-node

# Execute code with TypeScript.
ts-node -e 'console.log("Hello, world!")'

# Execute, and print, code with TypeScript.
ts-node -p '"Hello, world!"'

# Pipe scripts to execute with TypeScript.
echo "console.log('Hello, world!')" | ts-node
```

![TypeScript REPL](https://github.com/TypeStrong/ts-node/raw/master/screenshot.png)

### Programmatic

You can require `ts-node` and register the loader for future requires by using `require('ts-node').register({ /* options */ })`. You can also use file shortcuts - `node -r ts-node/register` or `node -r ts-node/register/transpile-only` - depending on your preferences.

**Note:** If you need to use advanced node.js CLI arguments (e.g. `--inspect`), use them with `node -r ts-node/register` instead of the `ts-node` CLI.

### Mocha

```sh
mocha --require ts-node/register --watch-extensions ts,tsx "test/**/*.{ts,tsx}" [...args]
```

**Note:** `--watch-extensions` is only used in `--watch` mode.

### Tape

```sh
ts-node node_modules/tape/bin/tape [...args]
```

### Gulp

```sh
# Create a `gulpfile.ts` and run `gulp`.
gulp
```

### Visual Studio Code

Create a new node.js configuration, add `-r ts-node/register` to node args and move the `program` to the `args` list (so VS Code doesn't look for `outFiles`).

```json
{
    "type": "node",
    "request": "launch",
    "name": "Launch Program",
    "runtimeArgs": [
        "-r",
        "ts-node/register"
    ],
    "args": [
        "${workspaceFolder}/index.ts"
    ]
}
```

## How It Works

**TypeScript Node** works by registering the TypeScript compiler for `.tsx?` and `.jsx?` extension (when `allowJs == true`). When node.js has an extension registered (via `require.extensions`), it will use the extension internally for module resolution. When an extension is unknown to node.js, it handles the file as `.js` (JavaScript).

**P.S.** This means if you don't register an extension, it is compiled as JavaScript. When `ts-node` is used with `allowJs`, JavaScript files are transpiled using the TypeScript compiler.

## Loading `tsconfig.json`

**Typescript Node** loads `tsconfig.json` automatically. Use `--skip-project` to the loading `tsconfig.json`.

**Tip**: You can use `ts-node` together with [tsconfig-paths](https://www.npmjs.com/package/tsconfig-paths) to load modules according to the `paths` section in `tsconfig.json`.

## Configuration Options

You can set options by passing them before the script path, via programmatic usage or via environment variables.

```sh
ts-node --compiler ntypescript --project src/tsconfig.json hello-world.ts
```

### CLI Options

Supports `--print`, `--eval` and `--require` from [node.js CLI options](https://nodejs.org/api/cli.html).

* `--help` Prints help text
* `--version` Prints version information

### CLI and Programmatic Options

_Environment variable denoted in parentheses._

* `-T, --transpileOnly` Use TypeScript's faster `transpileModule` (`TS_NODE_TRANSPILE_ONLY`)
* `--cacheDirectory` Configure the output file cache directory (`TS_NODE_CACHE_DIRECTORY`)
* `-I, --ignore [pattern]` Override the path patterns to skip compilation (`TS_NODE_IGNORE`)
* `-P, --project [path]` Path to TypeScript JSON project file (`TS_NODE_PROJECT`)
* `-C, --compiler [name]` Specify a custom TypeScript compiler (`TS_NODE_COMPILER`)
* `-D, --ignoreDiagnostics [code]` Ignore TypeScript warnings by diagnostic code (`TS_NODE_IGNORE_DIAGNOSTICS`)
* `-O, --compilerOptions [opts]` JSON object to merge with compiler options (`TS_NODE_COMPILER_OPTIONS`)
* `--files` Load files from `tsconfig.json` on startup (`TS_NODE_FILES`)
* `--pretty` Use pretty diagnostic formatter (`TS_NODE_PRETTY`)
* `--no-cache` Disable the local TypeScript Node cache (`TS_NODE_CACHE`)
* `--skip-project` Skip project config resolution and loading (`TS_NODE_SKIP_PROJECT`)
* `--skip-ignore` Skip ignore checks (`TS_NODE_SKIP_IGNORE`)

### Programmatic Only Options

* `transformers` An array of transformers to pass to TypeScript
* `readFile` Custom TypeScript-compatible file reading function
* `fileExists` Custom TypeScript-compatible file existence function

## Watching and Restarting

**TypeScript Node** compiles source code via `require()`, watching files and code reloads are out of scope for the project. If you want to restart the `ts-node` process on file change, existing node.js tools such as [nodemon](https://github.com/remy/nodemon), [onchange](https://github.com/Qard/onchange) and [node-dev](https://github.com/fgnass/node-dev) work.

There's also [`ts-node-dev`](https://github.com/whitecolor/ts-node-dev), a modified version of [`node-dev`](https://github.com/fgnass/node-dev) using `ts-node` for compilation and won't restart the process on file change.

## License

MIT

[npm-image]: https://img.shields.io/npm/v/ts-node.svg?style=flat
[npm-url]: https://npmjs.org/package/ts-node
[downloads-image]: https://img.shields.io/npm/dm/ts-node.svg?style=flat
[downloads-url]: https://npmjs.org/package/ts-node
[travis-image]: https://img.shields.io/travis/TypeStrong/ts-node.svg?style=flat
[travis-url]: https://travis-ci.org/TypeStrong/ts-node
[coveralls-image]: https://img.shields.io/coveralls/TypeStrong/ts-node.svg?style=flat
[coveralls-url]: https://coveralls.io/r/TypeStrong/ts-node?branch=master