Custom Iterator:
================

// Grocery Store Product Category

class GrocessoryStore{
    // constructor creation
    constructor(){
        this.categories = {
            fruits:["Apple","Banana","Ornage","Grapes"],
            vegetables:["Carrot","Broccolli","Spinach"],
            dairy:["Milk","Cheese","Yogurt"]
        };
    }
    // defining custome iterator
    [Symbol.iterator](){
        const categoryKeys = Object.keys(this.categories);
        let categoryIndex = 0;
        let itemIndex = 0;
        return{
            next:() =>{
                // check if there are more items in the current category
                if(itemIndex < this.categories[categoryKeys[categoryIndex]].length){
                    return{
                        value:this.categories[categoryKeys[categoryIndex]][itemIndex++],
                        done:false
                    };
                }
                else{
                    return{
                        done:true
                    }
                }
            },
        };
    }
}

const store = new GrocessoryStore();

for(const p of store){
    console.log(p);
}

===================================================================
Functions:
==========
functions can always write/define in outside of the class only.
but methods can define inside the class.

// Calculation of Total price with Tax

function calculateTotalPrice(price,taxRate){
    return price + (price * taxRate);
}

const itemPrice = 9999
const taxRate = 0.16;

let totalPrice = calculateTotalPrice(itemPrice,taxRate);
console.log("Total Price of the product = ",totalPrice);

==============================================================
// Greet the user based on the time
let greetUser = function(name){
    const hour = new Date().getHours();
    let greetings;
    
    if(hour < 12){
        greetings = "Good Morning";
    }
    else if(hour < 18){
        greetings = "Good Afternoon";
    }
    else{
        greetings = "Good Evening";
    }
    
    return `${greetings},${name}`;
}

console.log(greetUser("Ashish"));

========================================================
// Filter Items in a shopping list

function findItems(shoppingList,query){
    return shoppingList.filter(item => item.toLowerCase().includes(query.toLowerCase()));
}

let shoppingList = ["Apples","Bananas","Oranges","Grapes"];

console.log(findItems(shoppingList,"AP"));