add-ws-handler

This adds a no-features websockets middleware handler to an app. It's intended for use with express, but technically I guess you can use it with anything? This module is really quite awkward and you will almost certainly be better off with an alternative.

• express-ws
• express-websocket

Unfortunately, express-ws didn't work for my use case (due to the way we're setting up express, which is out of my control), and it's using ws@3 instead of ws@5, so!

usage

For a server,

const express = require('express');
const addWebsocketHandler = require('add-ws-handler');

const app = express();
const server = app.listen(0);
addWebsocketHandler({ app, server });

app.ws(
  '/path',
  (req, ws, next) => {
    ws.send('hi');
    next();
  },
  (req, ws, next) => ws.send('hello')
);

and from a client,

const WebSocket = require('ws');
const ws = new WebSocket(`ws://localhost:${server.address().port}/path`);
ws.on('message', console.log);

The addWebsocketHandler function takes an object with two required parameters and two optional parameters:

• app: (required) the object to attach the ws function to.

• server: (required) the server that will be accepting requests and in particular will be emitting an 'upgrade' event when the it receives a WebSocket request

• prefix: (optional) if the router or app will be mounted on a prefix, it should be passed in here so that we can append it to the paths that are registered:

  addWebsocketHandler({ app, server, prefix: '/prefix' });
  app.ws('/path', ...);
  
  // the above would respond to /prefix/path, not /path

• prototype: (optional) Express adds a bunch of stuff to the http.IncomingMessage prototype. To make the req object a little more familiar, you can pass a prototype and we'll set the prototype of the req object for you.

  const Express = require('express');
  addWebsocketHandler({ app, server, prototype: Express.request  });
  
  app.ws('/path', (req, ws, next) => {
    // req.header() is defined as in Express, even though
    // http.IncomingMessage doesn't have it on its own
  });