This and Arrow function in JavaScript.

"This" keyword -> Refers to current context.

console.log(this) 
// O/P -> an empty object initially.
const user = {
    user : "harsh"
    roll :28,

    welcomeMessage : function(){
        console.log(`${this.user} ,welcome)
        }
    }

user.welcomeMessage() // O/P -> harsh welcome

if we console.log(this) in chrome browser console this will print global object

which in the case of a browser environment, is usually the window object.

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Arrow function :-

Arrow functions in JavaScript provide a concise syntax for writing function expressions. They were introduced in ES6 (ECMAScript 2015) and offer a more concise syntax compared to traditional function expressions.

const addTwo = (num1,num2) =>{

    return num1 + num2 //explicit return 
}

const addTwo = (num1,num2) => num1 + num2; // implicit return.

const addTwo = (num1,num2) => (num1 + num2); //important.

if I give { } then I will have to write return keyword.

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IIFE (Immediately Invoked Function Expression)

It is a common way to write function in javascript where a function is defined and executed immediately.

(function chai (){
    console.log("Connected")
})
chai() //traditional way to define and call function


//IFFE

(function chai (){
    console.log("Connected")
}) ( ) ; //semicolon is needed so that other IFFE also work(mainly when we write 2 or 3 IFFE)
// The trailing () immediately invokes the function expression.

( ) ( ) => IFFE

// To avoid pollution of global scope we use IFFE.
//Global scope k pollution se bachne k liye we use IFFE

( (name ) => {
    console.log(`connected ${name}`)
}) ("harsh")  
//when there is any parameter.