Quansync NPM | npm.io

quansync

Create sync/async APIs with usable logic.

Quantum + Sync - "Superposition" between sync and async.

Typesafe
ESM, modern JavaScript
Zero dependencies

Heavily inspired by genasync by @loganfsmyth.

Usage

pnpm i quansync

import fs from 'node:fs'
import { quansync } from 'quansync'

// Create a quansync function by providing `sync` and `async` implementations
const readFile = quansync({
  sync: (path: string) => fs.readFileSync(path),
  async: (path: string) => fs.promises.readFile(path),
})

// Create a quansync function by providing a generator function
const myFunction = quansync(function* (filename) {
  // Use `yield*` to call another quansync function
  const code = yield* readFile(filename, 'utf8')

  return `// some custom prefix\n${code}`
})

// Use it as a sync function
const result = myFunction.sync('./some-file.js')

// Use it as an async function
const asyncResult = await myFunction.async('./some-file.js')

Why

// TODO:

How it works

// TODO:

Benchmark

Run the following command to benchmark the performance of quansync:

pnpm run build && pnpm run benchmark

Benchmark results indicate that each yield incurs an overhead of approximately 150 ns, comparable to that of await sync(). (On Apple M1 Max)

Build-time Macro

If you don't like the function* and yield* syntax, we also provide a build-time macro via unplugin-quansync allowing you use quansync with async/await syntax, while still able to get the sync version out of that.

Here is an example:

import fs from 'node:fs'
import { quansync } from 'quansync/macro'

// Create a quansync function by providing `sync` and `async` implementations
const readFile = quansync({
  sync: (path: string) => fs.readFileSync(path),
  async: (path: string) => fs.promises.readFile(path),
})

// Create a quansync function by providing an **async** function
const myFunction = quansync(async (filename) => {
  // Use `await` to call another quansync function
  const code = await readFile(filename, 'utf8')

  return `// some custom prefix\n${code}`
})

// Use it as a sync function
const result = myFunction.sync('./some-file.js')

// Use it as an async function
const asyncResult = await myFunction.async('./some-file.js')

For more details on usage, refer to unplugin-quansync's docs.