swc-node, the Fastest TypeScript/JavaScript Compiler

The Fastest TypeScript Compilation Tool

If you've been following deno, you may have noticed that deno has expanded its TypeScript ecosystem with many high-performance toolchains implemented in Rust, such as deno_lint and deno_fmt.

These toolchains are all built on top of the swc-project/swc project. swc is a TypeScript/JavaScript compiler implemented in Rust, delivering 5 to 20 times better performance than babel/ts.

swc officially provides a node binding, but the official version has several issues:

• It uses neon for the Node.js binding. neon has some performance disadvantages compared to Node.js's n-api at the binding layer and is not ABI stable. This means multiple binaries need to be compiled for different Node/V8 versions. The author has already migrated to napi-rs with my help. Once swc supports native plugins, @swc-node will directly use the official node implementation.
• Prebuilt binaries are distributed by downloading from GitHub assets during postinstall, which is blocked by the GFW in mainland China.
• Too many high-level abstractions are done in the native layer (class wrappers, multiple layers of serialize/deserialize for parameters), which further degrades performance.

To address these issues, the swc-node project was created: swc-node

Compared to the official @swc/core, swc-node has the following advantages:

• Implemented using N-API, compatible with all Node.js versions 8.9+
• No postinstall — everything is downloaded in a minimal form from npm, making it easy to use various npm registry mirrors for faster downloads
• Better performance
• Better support for the Node.js ecosystem, such as jest and swc-register (with future support for swc-loader and other toolchains)

In terms of performance, there is a simple benchmark in the GitHub repo that compiles RxJS's AjaxObservable.ts to ES2015 + CommonJS JavaScript (ES5 target is not used here because esbuild does not support targeting ES5):

Hardware Info:

Model Name: MacBook Pro
Model Identifier: MacBookPro15,1
Processor Name: 6-Core Intel Core i7
Processor Speed: 2.6 GHz
Number of Processors: 1
Total Number of Cores: 6
L2 Cache (per Core): 256 KB
L3 Cache: 12 MB
Hyper-Threading Technology: Enabled
Memory: 16 GB

• Transform Sync

@swc-node/core x 368 ops/sec ±4.18% (84 runs sampled)
esbuild x 42.16 ops/sec ±1.76% (55 runs sampled)
typescript x 24.52 ops/sec ±14.38% (51 runs sampled)
babel x 22.08 ops/sec ±10.17% (44 runs sampled)
Transform rxjs/AjaxObservable.ts benchmark bench suite: Fastest is @swc-node/core

• Transform Async Parallel

@swc-node/core x 946 ops/sec ±2.36% (74 runs sampled)
esbuild x 931 ops/sec ±3.56% (65 runs sampled)
Transform rxjs/AjaxObservable.ts parallel benchmark bench suite: Fastest is @swc-node/core,esbuild

After adopting @swc-node/jest, the test execution time for a pure TypeScript project I'm responsible for at work was significantly reduced:

// jest.config.js

module.exports = {
  verbose: true,
  transform: {
    '^.+\\.(t|j)sx?$': '@swc-node/jest',
  },
}

ts-jest:

Test Suites: 48 passed, 48 total
Tests:       239 passed, 239 total
Snapshots:   49 passed, 49 total
Time:        49.808 s
Ran all test suites.
✨  Done in 54.35s.

@swc-node/jest:

Test Suites: 49 passed, 49 total
Tests:       250 passed, 250 total
Snapshots:   53 passed, 53 total
Time:        9.921 s
Ran all test suites.
✨  Done in 15.79s.

Caveats:

Although swc is fast and capable, it still has some rough edges. You should be aware of the following trade-offs before using it:

Compilation output has not been validated at large scale:

Since the TypeScript compiler was written from scratch, swc simply hasn't been in use long enough. During the process of integrating it into projects at work, I discovered several compilation bugs. Therefore, it is currently not recommended for compiling production code. Using it in dev environments or for compiling test code are both good choices.

In the @swc-node project, if you encounter files with compilation issues, you can use the fallbackToTs option to have specific files fall back to TypeScript compilation.

Currently only supports three platforms: linux-gnu-64 / macOS / Win 64

If you want to use @swc-node on Android devices, linux musl environments (linux musl is now supported), or Windows ARM/ia64, you may need to wait a while.