make-synchronous

Make an asynchronous function synchronous

This is the wrong tool for most tasks! Prefer async APIs whenever possible.

The benefit of this package over packages like deasync is that this one is not a native Node.js addon (which comes with a lot of problems). Instead, this package executes the given function synchronously in a worker or subprocess.

Works in Node.js only — not the browser.

Install

npm install make-synchronous

Usage

Runs in a worker thread by default:

import makeSynchronous from 'make-synchronous';

const fn = makeSynchronous(async number => {
    const {default: delay} = await import('delay');

    await delay(100);

    return number * 2;
});

console.log(fn(2));
//=> 4

To run in a subprocess instead:

import makeSynchronous from 'make-synchronous/subprocess';

makeSynchronous(async () => {
    // Runs in a subprocess.
});

Subprocess execution is slower, but has the benefit of full process isolation.

API

makeSynchronous(asyncFunction | string)

Returns a wrapped version of the given async function or a string representation to a async function which executes synchronously. This means no other code will execute (not even async code) until the given async function is done.

The function is executed in a worker or subprocess, so you cannot access variables or imports from outside its scope. Use await import(…) to import dependencies inside the function.

Uses MessagePort#postMessage() or the V8 serialization API to transfer arguments, return values, errors between the worker or subprocess and the current process. Most values are supported — except functions and symbols.

Related

• make-asynchronous - Make a synchronous function asynchronous by running it in a worker
• sleep-synchronously - Block the main thread for a given amount of time
• make-synchronized - For advanced cases like fully synchronizing an existing module or needing top-level imports