@go22/port0

Check whether a TCP port is in use and find a random available port. Requires Node.js 18 or newer.

Install

npm install @go22/port0

Usage

import { genPort, isPortInUse } from '@go22/port0';

await isPortInUse(3000); // true or false
await isPortInUse('3000'); // true or false

await genPort(); // random available port from 1024 through 65535
await genPort(3000); // random available port from 3000 through 65535
await genPort(3000, 4000); // random available port from 3000 through 4000

Both range boundaries are inclusive. genPort checks each candidate no more than once and rejects with a RangeError if every port in the range is in use.

Availability is inherently a point-in-time check. Another process can claim a returned port before your application binds to it.

Because of this race condition, the intended use is to bind or connect with the randomly generated port immediately, minimizing the risk of a collision.

License

MIT