JSPM – find-free-ports@3.1.1

Package Exports

find-free-ports
find-free-ports/index.js

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (find-free-ports) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

This is a very small package that allows developers to find free ports on the local system. Unlike most other "find-free-port" utilities, this library allows scanning for multiple free ports at once, making sure that there are no doubles in the result.

✔️ TypeScript support

✔️ No dependencies

✔️ Should work on all major NodeJS versions

✔️ Now automatically tested for mistakes

This library has been benchmarked and parallelises the port checks using a customisable number of workers for optimal performance. The alogithm does not create a new anonymous socket for each port, but instead iterates in parallell over the system's port numbers. This is both faster and less resource-intensive.

🔍 Found an issue? Please let me know in the issue tracker and we'll get it fixed ASAP.

npm i find-free-ports

Usage

Import the library:

import findFreePorts from "find-free-ports"

const findFreePorts = require('find-free-ports');

Next, call the main function with the amount of free ports you need:

async function startMultipleServers() {
  const [a, b, c, d] = await findFreePorts(4);
  // now do something interesting with the new ports ...
}

API

findFreePorts(count?, opts?)

import { findFreePorts } from "find-free-ports"

Search for the specified amount of free ports on the local machine. If count is left unspecified, it defaults to 1. opts may be a dictionary containing one of the following keys:

isFree: custom function that is used to check whether the given port is free
startPort: start scanning for free ports starting from this port number. Defaults to 1025.
endPort: prevent the scanner from exceeding this port number. Defaults to 65535.
jobCount: how much workers that may at most be looking for free ports

isFreePort(port)

import { isFreePort } from "find-free-ports"

Check whether the given port is free by trying to set up a socket.

This function returns a promise containing either true or false depending on whether the port was available.

FindFreePortsOptions

import { FindFreePortsOptions } from "find-free-ports"

A TypeScript interface that lists all valid options that may be passed as the opts parameter to findFreePorts().

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License

The MIT License