Description

Find free port synchronously, useful when you need to get the port directly without callback.

Like config webpack-dev-server with port automatically.

module.exports = {
    ...
    output: '...',
    devServer: {
        ...
        port: "a free port"
    }
};

Installation

npm install find-free-port-sync --save-dev

Options

start

type: number | default: 1

Start of range to find, should be greater than 0

end

type: number | default: 65534

End of range to find, should be less than 65535

num

type: number | default: 1

Number of ports to find, relates to the return value

• When num === 1, return a free random port if found, null if not
• When num > 1, return an array of free [port] orderly if found, empty array [] if not

ip

type: string | default: 0.0.0.0|127.0.0.1

It will scan local adress by default, specify an ip here

port

type: number | default: null

If port is defined, it will return whether the port is free around start end ip option

Examples

Find a free port for local address

let findFreePort = require('find-free-port-sync');

let port = findFreePort();

Find 10 free ports between 10000 and 30000 for 192.168.1.1

let findFreePort = require('find-free-port-sync');

let port = findFreePort({
    start: 10000,
    end: 30000,
    num: 10,
    ip: '192.168.1.1'
});

Check if a port is free

let findFreePort = require('find-free-port-sync');

let portIsOk = findFreePort({
    port: 12345
});