Nodejs - Arrow Functions

Arrorw Functions :

    

        -> Its a shortest way to define functions.

             EXAMPLE:    

            

            Without Parameter

                    var kamal =()=>{console.log("Its a arrow functions")}

                   

                     kamal()            ///call function

            With Parameter

                    var kamal =(a)=>{console.log("value of a is :"+a)}

                    

                    kamal(5)          ///call function

            With Multiple Parameter

                    var kamal =(a,b)=>{

                                

                    var  c=a+b

                    console.log("value of c is :"+c)}

                    

                    kamal(5,5)          ///call function

OUTPUT- value of c is :10

Nodejs - Anonymous Functions

 Anonymous Functions

    -> define variable then function

    Ex.-        !) Without parameter.... 

                     ver kamal = function(){

                        console.log("Its a anontmous function");

                    }

                    kamal()              ///call functions

                !!) With parameter...

                    var kamal = funtion(a,b){

                     var c = a+b

                    console.log("The value of  c is : "+c)

                     }

                    kamal(5,5)          //call functions

OUTPUT -  The value of  c is :10

NOTE: There is no name infront of function thats why its a anonymous function.

NodeJs - Node Http & Query String

Basic Conecpts For Creating server and response code

Its a inbuilt modul with help of this module we can perform meny operationsIt Handle - Request & Response beacause it is a Hypertext Text Transfer Protocol(get request from user and give response to server)

1) For creating server we need Http module..

2) Url Handling : For Handlng Url we can use

var http = require('http');  --> inbuild module it access via direct requre method can access

var server = http.createServer(function(req , res){       ///create server

//Request Status , Content Type

server.writeHead(200,{"content-type":"text/plain"})

var url = req.url;                 //Url Handling

res.write(url)

res.end('Response End')     //print message

}) .listen(3000);

Note : Query String = Send Variable in browser with url

Url Handling

var http = require('http');  --> inbuild module it access via dirct method

var url = require('url');             //Handling Querystring

var server = http.createServer(function(req , res){       ///create server

server.writeHead(200,{"content-type":"text/plain"})

var result = url.parse(www.google.com?id=10, true).query;

res.write(res.name);   //things whinch want to get like name

}) .listen(3000);

Run-> localhost://300

Kotlin - Functions

 function with two Int parameters and Int return type.

fun sum(a: Int, b: Int): Int {

    return a + b

}

sum of 3 and 5 is 8

Open in Playground →

Target platform: JVMRunning on kotlin v.1.6.0

A function body can be an expression. Its return type is inferred.

fun sum(a: Int, b: Int) = a + b

sum of 19 and 23 is 42

Kotlin- When

NOTE :1) Whenever we have more then on condition that condition use "when" its a enhance version of switch condition

fun main(){

val userType = "admin"

when(userType){

"admin"->{

println("You'r admin")

}

"editor"->{

println("You'r editor")

}

"author"->{

println("You'r author")

}

else->{

println("You'r Other")

}

}

}

Output: You'r admin

Kotlin - Null Safty

 note : 1) Bydefault All variable non-null 

   2) For Accecpting this null value we have to put '?' with string. 

   3) If variable is null and want to access the properties of variable in that case use 'varible?.' 

   4) if confirm varible is not null then we can use '!!' but if not sure dont use it trow null pointer exception.

var name:String? = null

val Lname:String = "Nishad"

firstname

println("Hello${name?.length}")

Kotlin First Program 'Hello word'

1. Kotlin code is usually defined in packages. Package specification is optional: If you don't specify a package in a source file, its content goes to the default package.
2. An entry point to a Kotlin application is the main function. Since Kotlin 1.3, you can declare main without any parameters. The return type is not specified, which means that the function returns nothing.
3. println writes a line to the standard output. It is imported implicitly. Also note that semicolons are optional.

Example:

val name:String="Kamal"

val Lname:String="Nishad"

fun main(){

println("Hello $name $Lname")

}

OUTPUT: Hello Kamal Nishad