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Five-minute quickstart

Requirements: IOSignal JS 7.2.0, Node.js 22.16.0 or later, npm, and three terminals. Success: the receiver prints hello#message and Hello, IOSignal!.

Start the server, subscribe the receiver, then send a message through the server.

Prefer a complete web app? Start with runnable examples or choose a path.

1. Prepare a project​

mkdir iosignal-hello
cd iosignal-hello
npm init -y
npm install --save-exact iosignal@7.2.0

The .mjs extension enables ES modules without changing package.json.

2. Start the server​

Save as server.mjs:

import { Server } from 'iosignal';

const server = new Server({ port: 7777 });
server.on('ready', () => console.log('Server ready: ws://localhost:7777'));

In terminal 1, run node server.mjs and leave it running.

3. Start the receiver​

Save as receiver.mjs:

import { IO } from 'iosignal';

const io = new IO('ws://localhost:7777');
io.listen('hello#message', (tag, message) => {
  console.log(tag, message);
});
io.on('ready', () => console.log('Receiver ready:', io.cid));
io.on('error', console.error);

In terminal 2, run node receiver.mjs and wait for Receiver ready. listen() registers the handler and schedules the subscription when the connection becomes ready.

4. Send a message​

Save as sender.mjs:

import { IO } from 'iosignal';

const io = new IO('ws://localhost:7777');
io.on('ready', () => {
  io.signal('hello#message', 'Hello, IOSignal!');
  console.log('Message sent');
});
io.on('error', console.error);

In terminal 3, run node sender.mjs. The receiver should print hello#message Hello, IOSignal!. Here hello is the channel and message is the topic. Stop each process with Ctrl+C.

Next steps​