## The CometD Project

Welcome to the [CometD](https://cometd.org) Project, a scalable comet 
(server push) and websocket messaging library for the web.

This repository mirrors the JavaScript sources hosted at the [main
CometD repository](https://github.com/cometd/cometd).
Those JavaScript sources are not suitable to be consumed with NPM,
and are therefore re-arranged in this repository for to make it simpler
to use CometD with NPM.

### Versions

* `8.0.x` ⇒ based on CometD 8.0.x - full ECMAScript 6 (modules, classes, `let`, `const`, arrow functions)
* `7.0.x` ⇒ based on CometD 7.0.x - minimal ECMAScript 6 (`let`, `const` and arrow functions)
* `6.0.x` ⇒ N/A
* `5.0.x` ⇒ based on CometD 5.0.x - minimal ECMAScript 5 (`var` everywhere)

Version `6.0.x` is not released to NPM since it's identical to `7.0.x`.  
The `6.0.x` numbering exists only because the main CometD project, on the server side, is different from `7.0.x`, but on the client side there is no difference.

### License

The CometD source code is released under the Apache 2.0 License.

### NPM Installation

```
npm install cometd
```

### ES6 Usage

```js
// Import the CometD symbols.
import {CometD} from "./cometd/cometd.js";
import {TimeStampExtension} from "./cometd/TimeStampExtension.js";

// Create the CometD object.
const cometd = new CometD();

// Optionally, register an extension.
cometd.registerExtension("timestamp", new TimeStampExtension());

// Configure the CometD object.
cometd.configure({
    url: "http://host/cometd"
});

// Handshake with the server.
cometd.handshake((reply) => {
    if (reply.successful) {
        // Subscribe to receive messages from the server.
        cometd.subscribe("/topic", (message) => {
            const dataFromServer = message.data;
            // Use dataFromServer.
        });
    }
});
```