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Angular 2 RxJS Chat

An Angular 2 chat app using Angular 2, RxJS, Angular CLI, Webpack, TypeScript, Services, Injectables, Karma, Forms, and tslint by the ng-book 2 team

This repo shows an example chat application using RxJS and Angular 2. The goal is to show how to use the Observables data architecture pattern within Angular 2. It also features:

• Angular CLI, which configures Webpack with TypeScript, Karma, and tslint
• Writing async components that work with RxJS
• How to write injectable services in Angular 2
• And much more

Try the live demo here

Quick start

# clone the repo
git clone https://github.com/ng-book/angular2-rxjs-chat.git

# change into the repo directory
cd angular2-rxjs-chat

# install
npm install

# run
npm start

Then visit http://localhost:4200 in your browser.

Architecture

The app has three models:

• Message - holds individual chat messages
• Thread - holds metadata for a group of Messages
• User - holds data about an individual user

And there are three services, one for each model:

• MessagesService - manages streams of Messages
• ThreadsService - manages streams of Threads
• UserService - manages a stream of the current User

There are also three top-level components:

• ChatNavBar - for the top navigation bar and unread messages count
• ChatThreads - for our clickable list of threads
• ChatWindow - where we hold our current conversation

Services Manage Observables

Each service publishes data as RxJS streams. The service clients subscribe to these streams to be notified of changes.

The MessagesService is the backbone of the application. All new messages are added to the newMessages stream and, more or less, all streams are derived from listening to newMessages. Even the Threads exposed by the ThreadsService are created by listening to the stream of Messages.

There are several other helpful streams that the services expose:

For example, the MessagesService exposes the messages stream which is a stream of the list of the all current messages. That is, messages emits an array for each record.

Similarly, the ThreadsService exposes a list of the chronologically-ordered threads in orderedThreads and so on.

Understanding how RxJS streams can be tricky, but this code is heavily commented. One strategy to grokking this code is to start at the components and see how they use the services. The other strategy is to get a copy of ng-book 2 where we explain each line in detail over ~60 pages.

Bots

This app implements a few simple chat bots. For instance:

• Echo bot
• Reversing bot
• Waiting bot

Detailed Installation

Step 1: Install Node.js from the Node Website.

We recommend Node version 4.1 or above. You can check your node version by running this:

$ node -v
vv4.1...

Step 2: Install Dependencies

npm install

Running the App

npm run go

Then visit http://localhost:4200 in your browser.

Running the Tests

You can run the unit tests with:

npm run test

Future Plans

There are two big changes we plan to make to this repo:

1. Add HTTP Requests

Currently the bots are all client-side and there are no HTTP requests involved in the chats.

We will move the chat bots to a server and integrate API requests into this project once the Angular 2 HTTP client development has settled down.

2. ON_PUSH change detection

Because we're using observables, we can improve the performance of these components by using ON_PUSH change detection. Again, once Angular 2 development stabilizes, we'll be making this change.

Contributing

There are lots of other little things that need cleaned up such as:

• More tests
• Cleaning up the vendor scripts / typings
• Simplifying the unread messages count

If you'd like to contribute, feel free to submit a pull request and we'll likely merge it in.

Getting Help

If you're having trouble getting this project running, feel free to open an issue, join us on Gitter, or email us!

ng-book 2

This repo was written and is maintained by the ng-book 2 team. In the book we talk about each line of code in this app and explain why it's there and how it works.

This app is only one of several apps we have in the book. If you're looking to learn Angular 2, there's no faster way than by spending a few hours with ng-book 2.

License

MIT