Node.js is often a System developed on Chrome's JavaScript runtime for easily building quick, scalable community applications. Node.js works by using an celebration-driven, non-blocking I/O design that makes it light-weight and effective, great for info-intense genuine-time purposes that operate across dispersed products. NowJS is actually a framework constructed in addition to Node.js that connects the customer side and server facet JavaScript very easily.

The core of NowJS operation lies while in the now object. The now item is Specific because it exists over the server plus the consumer.

This suggests variables you established within the now item are routinely synced in between the shopper and the server. Also server features can be specifically identified as about the consumer and client capabilities is usually named straight from the server.

You may have a Doing the job HTTP server up and running in NodeJS with just some traces of code. For instance:


var http = require('http');

http.createServer(function (req, res)

res.writeHead(200, 'Written content-Variety': 'text/basic');

res.finish('Hello there Worldn');

).pay attention(8080);
This minimal snippet of code will generate an HTTP server, listen on port 8080, and ship back "Hello there Globe" For each and every request. Which is it. Practically nothing more wanted.

Utilizing NowJS, interaction among the shopper and server aspect is equally as straightforward.

Shopper Aspect:



In this particular code snippet, the shopper side sets a variable to 'someValue' and calls serverSideFunction(), that's declared only about the server.

Server Aspect:


Every person.now.serverSideFunction = purpose()

console.log(this.now.clientSideVariable);


The server facet is then in the position to entry clientSideVariable, which happens to be declared only over the client.

All the main points for example establishing connections and speaking modify of data involving the server and consumer are handed automagically by the framework.

In truth composing code using this framework is so uncomplicated, the NowJS howdy world case in point is actually a working chat customer and server created in less than a dozen traces of code. Go check it out.

As an easy physical exercise to receive cozy with the NowJS API, we could modify the chat consumer case in point to help multiple chat rooms. Let's Examine how uncomplicated it truly is.

Server Side (multiroom_server.js)

1. The first thing we have to do is modify the distributeMessage() perform to only send messages to people in the identical chat room since the user.


// Ship message to Absolutely everyone within the people group

All people.now.distributeMessage = perform(concept)

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

group.now.receiveMessage(this.now.identify+'@'+this.now.serverRoom, message);

;
We retail store the name from the server place on the consumer aspect (this.now.serverRoom). In the event the client calls the distributeMessage() operate we send out the information to everyone in the identical chat place by making use of getGroup() and using the group.now object in place of theeveryone.now item. (everyone is just a group that contains all people linked to the server).

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


Everybody.now.changeRoom = operate(newRoom)

var oldRoom = this.now.serverRoom;

//if outdated home just isn't null; then go away the old area

if(oldRoom)

var oldGroup = nowjs.getGroup(oldRoom);

oldGroup.removeUser(this.person.clientId);



// be part of The brand new room

var newGroup = nowjs.getGroup(newRoom);

newGroup.addUser(this.user.clientId);

// update the customer's serverRoom variable

this.now.serverRoom = newRoom;

;
The getGroup() technique fetches the team item if it exists and results in a gaggle if it isn't going to already exist. We make use of the teams addUser() and removeUser() techniques to move the consumer with the old area to The brand new home.

That's about this over the server side.

Consumer Facet (multiroom.html)

three. Initial we insert a fall down With all the list of server rooms.


Area oneHome 2Room threefour. Future we connect with the server aspect changeRoom() function once the user 1st connects and Each time the drop down is transformed.// on developing 'now' relationship, established the server placenow.Completely ready(functionality()// By default decide on the main chatroomnow.changeRoom($('#server-home').val()););// On alter of drop down, apparent textual content and prefabricated vaults alter server place$('#server-room').modify(operate()$("#messages").html(");now.changeRoom($('#server-home').val()););5. For additional credit score, we can allow the server to dynamically give the listing of rooms in the event the client connects.