Deno WebSocket Server 🔌

A WebSocket server library for Deno.

The raison d’être for this library is to provide a unified async iterator for the events of all connected WebSocket clients.

Note: This WebSocket server is not an EventEmitter (i.e. it does not use events with callbacks like websockets/ws). Instead, it specifies the asyncIterator symbol and should be used in conjunction with a for await...of loop, just like the Deno http server. The iterator return values are

type WebSocketServerEvent = {
    event: WebSocketEvent;
    socket: WebSocket;
};

where socket is the WebSocket from which the data was received on.

Usage

Simple server

import { serve } from 'https://deno.land/x/websocket_server/mod.ts'
const server = serve(":8080");
for await (const { event } of server) {
    console.log(event);
}

Echo / broadcast server

Check out the example echo/broadcast server.

FAQ

How do I create a WebSocket client?

This library provides a class only for WebSocket servers, not WebSocket clients, because it is straightforward to create clients with the std/ws module.

Here is a simple example:

import { connectWebSocket } from "https://deno.land/std/ws/mod.ts";
try {
    const socket = await connectWebSocket("ws://127.0.0.1:8080");
    for await (const event of socket) {
        console.log(event);
        if (typeof event === "string" && event === "Who is this?") {
            socket.send("It is me, a simple WebSocket client.");
        }
    }
} catch (err) {
    console.error(`Could not connect to WebSocket: '${err}'`);
}

Changelog

Changelog entries can be found at releases.

Acknowledgements

• Thanks to zorbyte for helping me understand enough about async iterators to implmenent the server

License

MIT