@swc-node/register

What is @swc-node/register?

@swc-node/register is an npm package that allows you to use SWC (a super-fast TypeScript/JavaScript compiler) to transpile your code on-the-fly when running Node.js applications. This package is particularly useful for developers who want to leverage the speed of SWC for TypeScript or modern JavaScript features without needing to precompile their code.

What are @swc-node/register's main functionalities?

On-the-fly TypeScript Compilation

This feature allows you to run TypeScript code directly in Node.js without precompiling it. The code sample demonstrates how to require the @swc-node/register package and run TypeScript code on-the-fly.

require('@swc-node/register');
const tsCode = `const greet = (name: string): string => `Hello, ${name}`;`;
console.log(greet('World'));

Modern JavaScript Syntax Support

This feature allows you to use modern JavaScript syntax (like ES6 arrow functions) in Node.js applications. The code sample shows how to require the @swc-node/register package and run modern JavaScript code on-the-fly.

require('@swc-node/register');
const es6Code = `const add = (a, b) => a + b; console.log(add(2, 3));`;
eval(es6Code);

Configuration Options

This feature allows you to customize the SWC compiler options. The code sample demonstrates how to pass configuration options to the @swc-node/register package to set the JavaScript target version.

require('@swc-node/register')({
  swc: {
    jsc: {
      target: 'es2017'
    }
  }
});
const code = `const x = async () => await Promise.resolve('done'); x().then(console.log);`;
eval(code);

Other packages similar to @swc-node/register

ts-node

ts-node is a TypeScript execution environment for Node.js. It allows you to run TypeScript code directly without precompiling. Compared to @swc-node/register, ts-node is slower because it uses the TypeScript compiler (tsc) instead of SWC.

babel-register

babel-register is a package that hooks into Node.js require to compile files on the fly using Babel. It supports a wide range of JavaScript syntax and features. Compared to @swc-node/register, babel-register is slower because Babel is not as fast as SWC.

esbuild-register

esbuild-register is a package that allows you to use esbuild to compile JavaScript and TypeScript code on-the-fly in Node.js. It is similar to @swc-node/register in terms of speed, as esbuild is also a very fast compiler.

README

@swc-node/register

Usage

const register = require('@swc-node/register')

register({
  ...
})

Mocha

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

ava

// package.json

{
  "ava": {
    "extensions": ["ts", "tsx"],
    "require": ["@swc-node/register"],
    "files": ["packages/**/*.spec.{ts,tsx}"]
  }
}