why we need to use arrow function in javascript code example

Example 1: js arrow function this

const person = {
    firstName: 'Viggo',
    lastName: 'Mortensen',
    fullName: function () {
        return `${this.firstName} ${this.lastName}`
    },
    shoutName: function () {
        setTimeout(() => {
            //keyword 'this' in arrow functions refers to the value of 'this' when the function is created
            console.log(this);
            console.log(this.fullName())
        }, 3000)
    }
}

Example 2: arrow function javascript

//If body has single statement
let myFunction = (arg1, arg2, ...argN) => expression

//for multiple statement
let myFunction = (arg1, arg2, ...argN) => {
    statement(s)
}
//example
let hello = (arg1,arg2) => "Hello " + arg1 + " Welcome To "+ arg2;
console.log(hello("User","Grepper"))
//Start checking js code on chrome inspect option