Nodejs Session01

Workshop
@
Ramnshee Infotech
By Jainul Musani
SESSION:01
1

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Node.Js
 Node.js is a cross-platform runtime environment
 Node.js provide a library to run JavaScript applications
outside the browser.
 Node.js is used for creating server-side and networking
web applications.
 It is open source and free to use.
 It can be downloaded from this
link https://nodejs.org/en/
Node.js = Runtime Environment +
JavaScript Library

About Node.js
 Node.js uses
 Event-Driven,
Non-Blocking I/O model
Lightweight and Efficient,
 Perfect for Data-Intensive real-time applications
Run across distributed devices
Node.js is a platform built on Chrome's JavaScript
runtime
easily building fast and scalable network
applications.
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Traditional Web Server Model
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Nodejs Process Model
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Different Parts of Node.js
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Features of Node.js
 1) Extremely fast:
 2) I/O is Asynchronous and Event Driven:
 3) Single threaded:
 4) Highly Scalable:
 5) No buffering:
 6) Open source:
 7) License: under the MIT license.
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Installation of Node.js
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Start with Node.js CLI
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 C:UsersJainul>node
Welcome to Node.js v12.17.0.
Type ".help" for more information.
> _
 > console.log("Good Morning...!!!")
Good Morning...!!!
undefined

Simple Commands with Node.js
 Create a .js file “node1.js”
 Write basic commands of Js and save the file.
Console.log(“Testing”);
Console.log(“Good Morning…!!!”);
 D:UsersJamtemp>node node1.js (.js is optional)
Testing
Good Morning....!!!
 D:UsersJamtemp> _
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Node.js REPL
 Read
 Evaluate
 Print
 Loop
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How to start REPL – (Nodejs CLI)
 C:UsersJainul>node
Welcome to Node.js v12.17.0.
Type ".help" for more information.
> _
 > console.log("Good Morning...!!!")
Good Morning...!!!
undefined
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REPL commands and Features
 Press Ctrl+C to terminate the current command.
Pressing Ctrl + C twice causes the REPL to quit.
Press Ctrl+D to exit the REPL.
 Pressing up and down arrow keys you can see command
history and modify previous commands.
 Press tab key to see the list of current commands. If you
type a single character followed by tab it will show the
list of keywords, functions, and variables starting with
that particular character.
 The REPL can handle multiline expression.
 The REPL provides a special variable _ (underscore)
which is used to pull the result of the last expression.
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> 1+2
3
> 1+2-3
0
> 1+(3-2)*4/2
3
>
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> var x = 10;
undefined
> var y = 20;
undefined
> x+y
30
> console.log(x+y);
30
undefined
>
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Node.js Underscore _ variable
 To get last result use underscore _ variable
> console.clear()
> a = 10
> b = 15
> a+b
25
> console.log(“last sum is: “ + _+5);
last sum is 30
>
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Node.js Loop structure ‘do-while’
 Loop Structure in
Node.js
> var a = 10
undefined
> i = 1
1
> do{
... console.log(i)
... i++;
... }while(i<a);
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>
1
2
3
4
5
6
7
8
9
>
Output:

Node.js Primitive Data Types
 Node.js includes following primitive types:
• String
• Number
• Boolean
• Undefined
• Null
• RegExp
 Everything else is an object in Node.js.
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Node.js Data Types
 Loose Typing
• JavaScript in Node.js supports loose typing like
the browser's JavaScript.
• Use var keyword to declare a variable of any
type.
• Object Literal
var obj = {
authorName: 'Raxit Dilhan',
language: 'Node.js'
}
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Function in NodeJs
File name: func1.js
function display(){
console.log("Function 1");
}
function dispPara(x){
console.log("Function with Para : ", x);
}
display();
dispPara(10);
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Buffer in NodeJs
 Node.js includes an additional data type
called Buffer (not available in browser's
JavaScript).
 Buffer is mainly used to store binary data,
while reading from a file or receiving packets
over the network.
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process object in NodeJs
Each Node.js script runs in a process.
It includes process object to get all the
information about the current process of
Node.js application.
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Defaults to local in NodeJs
Nodejs JavaScript is different from
browser's JavaScript when it comes to
global scope.
In the browser's JavaScript, variables
declared without var keyword become
global.
In Node.js, everything becomes local by
default.
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Access Global Scope in NodeJs
In a browser, global scope is the window
object. In Node.js, global object represents
the global scope.
To add something in global scope, you need
to export it using export or module.export.
The same way, import modules/object using
require() function to access it from the
global scope.
For example, to export an object in
Node.js, use exports.name = object.
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Access Global Scope in NodeJs
exports.mylib = {
 sum: function(a,b) {
 console.log(“Sum = “, a+b);
 },
 greet: function(msg) {
 console.log(“Hello…”, msg);
 }
}
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Nodejs Session01

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