swc - Ninjutsu Build

A package to create a ninjutsu-build rule for transpiling TypeScript and JavaScript files using SWC.

Unlike @ninjutsu-build/tsc, this plugin only transpiles and does not perform type checking or generate type declarations. This makes it faster and well-suited for use alongside @ninjutsu-build/tsc (for type declarations) so that typechecking and test execution can run in parallel.

Prerequisites

This project requires NodeJS (version 22 or later), npm, and @swc/cli.

Installation

Most likely you require @ninjutsu-build/swc, @ninjutsu-build/core, and @swc/cli as devDependency packages, which can be achieved by running the following npm command:

$ npm install @ninjutsu-build/core @ninjutsu-build/swc @swc/cli --save-dev

Basic Example

Given the following TypeScript file,

// src/add.ts
export function add(a: number, b: number): number {
  return a + b;
}

We can build a build.ninja file that will transpile src/add.ts to dist/add.js,

import { NinjaBuilder } from "@ninjutsu-build/core";
import { makeSWCRule } from "@ninjutsu-build/swc";
import { writeFileSync } from "node:fs";

// Create a `NinjaBuilder`
const ninja = new NinjaBuilder({
  ninja_required_version: "1.1",
  builddir: ".builddir",
});

// Create the `swc` rule, passing SWC arguments that apply to all build edges
const swc = makeSWCRule(ninja, {
  args: ["-C", "jsc.target=es2018", "-C", "module.type=commonjs"],
});

swc({
  in: "src/add.ts",
  out: "dist/add.js",
});

writeFileSync("build.ninja", ninja.output);

Run this script with node --experimental-strip-types configure.ts (or npx tsx configure.ts etc.) and then run ninja!

Overriding args per build edge

SWC arguments set at the rule level apply to every build edge, but can be overridden for individual build edges by passing args directly,

const swc = makeSWCRule(ninja, {
  args: ["-C", "jsc.target=es2018", "-C", "module.type=commonjs"],
});

// This edge overrides the module type to ES modules
swc({
  in: "src/index.mts",
  out: "dist/index.mjs",
  args: ["-C", "jsc.target=es2018", "-C", "module.type=es6"],
});