Node.js is actually a System developed on Chrome's JavaScript runtime for effortlessly building rapid, scalable network applications. Node.js takes advantage of an function-driven, non-blocking I/O product that makes it light-weight and successful, perfect for data-intense genuine-time purposes that operate across dispersed gadgets. NowJS is a framework designed on top of Node.js that connects the shopper aspect and server side JavaScript very easily.

The core of NowJS operation lies inside the now item. The now item is Exclusive since it exists on the server plus the consumer.

This suggests variables you set within the now item are instantly synced concerning the customer and the server. Also server capabilities could be instantly referred to as on the customer and client features may be termed directly from the server.

You might have a Functioning HTTP server up and functioning in NodeJS with just a couple strains of code. By way of example:


var http = require('http');

http.createServer(purpose (req, res)

res.writeHead(200, 'Information-Kind': 'textual content/plain');

res.conclusion('Hi there Worldn');

).hear(8080);
This small snippet of code will make an HTTP server, listen on port 8080, and send out back "Hello there Globe" For each request. That is it. Absolutely nothing additional required.

Working with NowJS, communication amongst the shopper and server aspect is equally as straightforward.

Customer Side:



With this code snippet, the client aspect sets a variable to 'someValue' and phone calls serverSideFunction(), which can be declared only to the server.

Server Side:


everyone.now.serverSideFunction = operate()

console.log(this.now.clientSideVariable);


The server side is then capable to access clientSideVariable, which can be declared only over the client.

All the small print which include setting up connections and speaking change of information involving the server and client are handed automagically with the framework.

In actual fact creating code working with this framework is so simple, the NowJS howdy earth example is actually a Performing chat client and server composed in underneath a dozen lines of code. Go check it out.

As a straightforward exercise to acquire at ease with the NowJS API, we are able to modify the chat customer case in point to assistance a number of chat rooms. Let us take a look at how straightforward it can be.

Server Facet (multiroom_server.js)

1. The first thing we have to do is modify the distributeMessage() functionality to only deliver messages to end users in a similar chat room since the consumer.


// Mail message to Every person while in the buyers group

Every person.now.distributeMessage = purpose(information)

var group = nowjs.getGroup(this.now.serverRoom);

group.now.receiveMessage(this.now.title+'@'+this.now.serverRoom, information);

;
We store the name on the server home around the consumer aspect (this.now.serverRoom). In the event the shopper calls the distributeMessage() perform we ship the information to everyone in exactly the same chat area by using getGroup() and utilizing the team.now item instead of theeveryone.now object. (everyone is just a bunch which contains all buyers connected to the server).

2. Up coming we have to cope with the shopper changing chat rooms.


Everybody.now.changeRoom = operate(newRoom)

var oldRoom = this.now.serverRoom;

//if outdated place is not really null; then leave the old space

if(oldRoom)

var oldGroup = nowjs.getGroup(oldRoom);

oldGroup.removeUser(this.consumer.clientId);



// be part of The brand new place

var newGroup = nowjs.getGroup(newRoom);

newGroup.addUser(this.person.clientId);

// update the shopper's serverRoom variable

this.now.serverRoom = newRoom;

;
The getGroup() method fetches the group object if it exists and produces a group prefabricated vaults if it will not exist already. We utilize the teams addUser() and removeUser() strategies to shift the client from the old space to the new area.

That is about this about the server facet.

Shopper Facet (multiroom.html)

three. To start with we increase a fall down with the list of server rooms.




Space 1

Area two

Place three


four. Next we get in touch with the server aspect changeRoom() operate if the consumer 1st connects and Each time the fall down is transformed.


// on developing 'now' link, set the server area

now.Prepared(operate()

// By default select the initial chatroom

now.changeRoom($('#server-area').val());

);

// On modify of drop down, very clear text and alter server home

$('#server-place').transform(purpose()

$("#messages").html(");

now.changeRoom($('#server-place').val());

);
five. For further credit rating, we will allow the server to dynamically supply the list of rooms when the consumer connects.