Saturday, 6 February 2016

NodeJS tutorial with Visual studio Code

 node.js tutorial for beginners with visual Studio Code

Download Visual Studio Code : Free IDE developed by microsoft which run under any platform.

Download Node JS :

What is node JS?

Node.js is an open-source, cross-platform runtime environment for developing server-side Web applications. Node.js worked under Chrome V8 JavaScript engine. Node.js was developed by Ryan Dahl in 2009 and its latest version is v0.10.36. Node.js is a runtime environment and library for running Javascript application outside the browser.



When to use Node

NodeJs is great for string or event based real time applications.
-       Streaming server
-        Chat Application
-       Real time and collaborative environment
-       Node is good if you need high concurrency but less CPU utilization.
-       Multiuser game

Node.Js is running under single thread.


Setting Up the NodeJS,


You will need to download and install the node.js runtime. Download NodeJS from here: http://nodejs.org/download/ and select windows and install based on requirement of 32bit or 64Bit. After install you can check the NodeJS have installed or not by C:\Program Files\nodejs.
There you can see the NPM – it is use to setup the node package manager.
Now you can open the nodeJs command from by start option Type nodeJs. Just type npm  -h.
It will display the command for npm.




First application of Node in Visual Studio Code

I created directive D:\NodeJs\nodesamples\01_helloworld  and created file as app.js.
Now open that file in visual code by below command as;


Now you can see it will open the visual studio code for you as like below and you have the file structure as:



Now lets write the code as console.log("hello world"); in app.js and run that application. Now go to debug at the last left icon(1) and run that application (2). As you are running the application first time it will ask to set up the environment select the node.js.(3)

Set up the configuration path as like below.



Now run the application and expected output value is Hello world will display in console.
Now you can see the result in console as;

Success: you have created your first application of hello world.

Let’s move to create the first webapplication;

You need to invoke the Http api first to your application as;

var http = require('http');    // You require the http api to invoke it


create the server
var server = http.createServer(function (req, res) {
    res.end('Hello World\n');
});


Defined the port on which server will run;
server.listen(3000);


Now run the application same as like below and you have full code like below;


Go to browser and type  http://localhost:3000 ; as you are running the application on 3000 port.
You will get output as;

REPL Terminal

REPL mis read Eval Print Loop, it is just like window console and there you can perform the operations.
It perform following desired task.
Read : Read users input, parse the input into Javascript and store into memory.
Eval : Evalaute the data structure.
Print : print the resul
loop : it will loop command until user close it by ctrl +c twice.,

To Start REPL.
Just type node in node.js command prompt.



Now you can check with the simple expression like;
>6 + 9



You can perform multiline expression also like;

REPL Commands
ctrl + c - terminate current command.
ctrl + d or ctrl + c twice - terminate the Node REPL.
Up/Down Keys - see the history and modify previous commands.
tab Keys - list of current commands.
.help - list of all commands.
.clear or .break - exit from multiline expression.

Read File In Node JS

Now suppose you want to read a file in nodeJs and want to display it into browser, for reading the file you need to take the reference as like;
var fs = require('fs');
Reading the text file as;
var con = fs.readFileSync('mytest.txt').toString();

Now you have code like;

You will get output in browser as :








Wonderful video found in youtube and taking the reference from there also but its quite lengthy;



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