Add support for WebSocket

[bfreis]

Hello,

A while ago I forked the browser-based CometD JS client to add support to NodeJS, with WebSocket. My general approach is very similar to what you have here: I defined window.setTimeout & friends, but I did a bit more of a hack-y solution regarding the window.location and document objects - it works perfectly well for my specific purposes. But I'm glad to see it officially done/supported now!

I actually build an "isomorphic" solution - that is, it works both on the browser and in NodeJS.

The code to support WebSocket in node is actually very simple. All you have to do is npm install --save ws, and then in the code simply add:

window.WebSocket = require('ws')

---

As a "nice to have", in case you want to make this isomorphic (yay!), here's how that can be accomplished:

package.json:

{
  ...
  "dependencies": {
    "ws": "^2.2.1"
  },
  "browser": {
    "ws": false,
    "./ws-wrapper.js": "./ws-wrapper-browser.js"
  }
  ...
}

ws-wrapper.js:

module.exports = require('ws')

ws-wrapper-browser.js

module.exports = WebSocket

That's it, done. The main code does require('./ws-wrapper.js'). In NodeJS, it resolves to the real ws-wrapper.js file which, in turn, requires the real ws module.

In a packer for a Web-based, the packer reads the "browser": {...} key in package.json and performs the replacement: when it see require('./ws-wrapper.js'), it actually reads the ws-wrapper-browser.js file. The "ws": false key is useful to prevent browser packing tools from even trying to import and include in the bundle the ws dependency, because that would completely break the browser-based build.

The solution works on Node, on the Browser, and even in React Native running on a mobile phone!

Would be awesome if you could add this - or at least the trivial support for WebSocket in node, without the isomorphic feature.

Thanks!
Bruno