javascript.js

// console.log can print something on console 
console.log("hello world");

"use strict";
// intro to variables

// variables can store some information
// we can use that information later
// we can change that information later

// declare a variable 

var firstName = "Saurabh";

// use a variable 
console.log(firstName);

// change value 

firstName = "Shaurya";

console.log(firstName);

// rules for naming variables 

// you cannot start with number 
// example :- 
// 1value (invalid)
// value1 (valid)

var value1 = 2;
console.log(value1);

// you can use only undersore _ or dollar symbol 
// first_name (valid)
// _firstname (valid) 

// first$name (valid)
// $firstname (valid)

// you cannot use spaces 
// var first_name = "Saurabh"; // snake case writing 
// var firstName = "Saurabh"; // camel case writing 
// first name (invalid)

// convention 
// start with small letter and use camelCase 

// let keyword 
// declare variable with let keyword 

let firstName = "harshit";
firstName = "Mohit";
console.log(firstName);

// declare constants 

const pi = 3.14;
console.log(pi);

// String indexing 

let firstName = "saurabhmanipandey";

//  h    a   r   s   h   i   t 
//  0    1   2   3   4   5   6

// console.log(firstName[0]);
// length of string 
// firstName.length 

console.log(firstName.length);

console.log(firstName[firstName.length-2]);

// last Index : length - 1 

// trim() 
// toUpperCase()
// toLowerCase()
// slice()

let firstName = "  Saurabh ";

// console.log(firstName.length);
// firstName = firstName.trim(); // "Saurabh12"
// console.log(firstName)
// console.log(firstName.length);
// firstName = firstName.toUpperCase();
// firstName = firstName.toLowerCase();
// console.log(firstName);

// start index 
// end index

let newString = firstName.slice(1); // Saurabh
console.log(newString);

// typeof operator 

// data types (primitive data types)
// string "saurabh"
// number 2, 4, 5.6 
// booleans 
// undefined
// null 
// BigInt
// Symbol

// let age = 22; 
// let firstName = "harshit";

// // console.log(typeof age);

// // 22 -> "22"
// // convert number to string. 
// age = age + "";
// console.log(typeof(age)); "22"


// // convert string to number. 

// let myStr = +"34";

// console.log(typeof myStr);

// let age = "18";
// age = Number(age);
// console.log(typeof age);
// string concatenation 

let string1 = "17";
let string2 = "10";

let newString1 = +string1 + +string2;
console.log(typeof newString1);

// template string 
let age = 24;
let firstName = "Shivansh"

// "my name is harshit and my age is 22 "
// let aboutMe = "my name is " + firstName + " and my age is " + age; 

let aboutMe = `my name is ${firstName} and my age is ${age}`

console.log(aboutMe);

// undefined 
// null

// let firstName;
// console.log(typeof firstName);
// firstName = "Pandey";
// console.log(typeof firstName, firstName);

// let myVariable = null;
// console.log(myVariable);
// myVariable = "Pandey";
// console.log(myVariable, typeof myVariable);
// console.log(typeof null);
// bug , error 

// BigInt
// let myNumber = BigInt(12);
// let sameMyNumber = 123n;
// // console.log(myNumber);
// // console.log(Number.MAX_SAFE_INTEGER);
// console.log(myNumber+ sameMyNumber);

// booleans & comparison operator 

// booleans 
// true, false 

// let num1 = 7;
// let num2 = "7";

// console.log(num1<num2);

// == vs === 
// console.log(num1 === num2);

// != vs !==

// console.log(num1 !== num2);

// truthy and falsy values 

// falsy values 


// false
// ""
// null 
// undefined
// 0

// if else condition 

// let age = 17;

// if(age>=18){
//     console.log("User can play ddlc");
// }else {
//     console.log("User can play mario");
// }

// let num = 13;

// if(num%2===0){
//     console.log("even");
// }else{
//     console.log("odd");
// }

// falsy values 


// false
// ""
// null 
// undefined
// 0

// truthy 
// "abc"
// 1, -1

// let firstName= 0;

// if(firstName){
//     console.log(firstName);
// }else{
//     console.log("firstName is kinda empty");
// }

// ternary operator 

// let age = 4;
// let drink;

// if(age>=5){
//     drink = "coffee";
// }else{
//     drink = "milk";
// }

// console.log(drink);

// ternary operator / conditional operator 

// let age = 3;
// let drink = age >= 5 ? "coffee" : "milk";
// console.log(drink);

// and  or operator 



// if(firstName[0] === "H"){
//     console.log("your name starts with H")
// }

// if(age > 18){
//     console.log("you are above 18");
// }

// if(firstName[0] === "H" && age>18){
//     console.log("Name starts with H and above 18");
// }else{
//     console.log("inside else");
// }
let firstName = "arshit";
let age = 16;

if(firstName[0] === "H" || age>18){
    console.log("inside if");
}else{
    console.log("inside else");
}

// nested if else

// winning number 19 

// 19 your guess is right 
// 17 too low 
// 20 too high 

let winningNumber = 19;
let userGuess = +prompt("Guess a number");

if(userGuess === winningNumber){
    console.log("Your guess is right!!");
}else{
    if(userGuess < winningNumber){
        console.log("too low !!!");
    }else{
        console.log("too high !!!");
    }
}


// if 
// else if 
// else if 
// else if 
// else 

// let tempInDegree = 50;


// if(tempInDegree < 0){
//     console.log("extremely cold outside");
// }else if(tempInDegree < 16){
//     console.log("It is cold outside");
// }else if(tempInDegree < 25){
//     console.log("wheather is okay ");
// }else if(tempInDegree < 35){
//     console.log("lets go for swim");
// }else if(tempInDegree < 45){
//     console.log("turn on AC");
// }else{
//     console.log("too hot!!");
// }

// console.log("hello");



// let tempInDegree = 50;


// if(tempInDegree < 0){
//     console.log("extremely cold outside");
// }else if(tempInDegree < 16){
//     console.log("It is cold outside");
// }else if(tempInDegree < 25){
//     console.log("wheather is okay ");
// }else if(tempInDegree < 35){
//     console.log("lets go for swim");
// }else if(tempInDegree < 45){
//     console.log("turn on AC");
// }else{
//     console.log("too hot!!");
// }

// console.log("hello there");



let tempInDegree = 4;

if(tempInDegree > 40){
    console.log("too hot");
}else if(tempInDegree > 30){
    console.log("lets go for swim");
}else if(tempInDegree > 20){
    console.log("weather is cool");
}else if(tempInDegree > 10){
    console.log("it is very cold outside");
}else{
    console.log("extremely cold");
}

console.log("hello");

// switch statement 


// let day = 7; 


// if(day === 0){
//     console.log("Sunday");
// }else if(day ===1){
//     console.log("Monday");
// }else if(day ===2){
//     console.log("Tuesday");
// }else if(day ===3){
//     console.log("Wednesday");
// }else if(day ===4){
//     console.log("Thrusday");
// }else if(day ===5){
//     console.log("Friday");
// }else if(day ===6){
//     console.log("Saturday");
// }else{
//     console.log("Invalid Day");
// }


let day = 9;

switch(day){
    case 0:
        console.log("Sunday");
        break; 
    case 1:
        console.log("Monday");
        break;
    case 2:
        console.log("Tuesday");
        break;
    case 3:
        console.log("Wednesday");
        break;
    case 4:
        console.log("Thrusday");
        break;
    case 5:
        console.log("Friday");
        break;
    case 6:
        console.log("Saturday");
        break;
    default:
        console.log("Invalid Day");
}
// while loop 

// 0 se 9 
// dry don't repeat yourself
let i = 0; // 1 2 3 4

while(i<=9){
    console.log(i);
    i++;
}
console.log(`current value of i is ${i}`);
console.log("hello");

// while loop example 
let num = 100;
// let total = 0; //1 + 2 +3
// let i = 0;


// while(i<=100){
//     total = total + i;
//     i++;
// }


// console.log(total);

// let total = (num*(num+1))/2;
// console.log(total);

// intro to for loop 
// print 0 to 9

for(let i = 0;i<=9;i++){
    console.log(i);
}

// console.log("value of i is ",i);
// for loop example 

let total = 0;

let num = 100;

for(let i = 1; i<=num; i++){
    total = total + i;
}

console.log(total);

// break keywork

// continue keyword 

// for(let i = 1; i<=10; i++){
//     if(i===4){
//         break;
//     }
//     console.log(i);
// }

// for(let i = 1; i<=10; i++){
//     if(i===4){
//         continue;
//     }
//     console.log(i);
// }
console.log("hello there");

// do while loop

// while(i<=9){
//     console.log(i);
//     i++;
// }

// let i = 10;
// do{
//     console.log(i);
//     i++;
// }while(i<=9);

// console.log("value of i is ", i);

// intro to arrays 
// reference type 
// how to create arrays

// ordered collection of items 

// let fruits = ["apple", "mango", "grapes"];
// let numbers = [1,2,3,4];
// let mixed = [1,2,2.3, "string", null, undefined];
// console.log(mixed);
// console.log(numbers);
// console.log(fruits[2]);
let fruits = ["apple", "mango", "grapes"];
let obj = {}; // object literal
// console.log(fruits);
// fruits[1] = "banana";
// console.log(fruits);
console.log(typeof fruits);
console.log(typeof obj);
console.log(Array.isArray(fruits));
console.log(Array.isArray(obj));

// array push pop 

// array shift unshift 

let fruits = ["apple", "mango", "grapes"];
console.log(fruits);
// push 
// fruits.push("banana");
// console.log(fruits);
// pop 
// let poppedFruit = fruits.pop();
// console.log(fruits);
// console.log("popped fruits is", poppedFruit);

// unshift 
// fruits.unshift("banana");
// fruits.unshift("myfruit");
// console.log(fruits);

// shift 
// let removedFruit = fruits.shift();
// console.log(fruits);
// console.log("removed fruits is ", removedFruit);

// primitve vs reference data types
// let num1 = 6;
// let num2 = num1;
// console.log("value is num1 is", num1);
// console.log("value is num2 is", num2);
// num1++;
// console.log("after incrementing num1")
// console.log("value is num1 is", num1);
// console.log("value is num2 is", num2);


// reference types 
// array 
let array1 = ["item1", "item2"];
let array2 = array1;
console.log("array1", array1);
console.log("array2", array2);
array1.push("item3");
console.log("after pushing element to array 1");
console.log("array1", array1);
console.log("array2", array2);

// how to clone array 

// how to concatenate two arrays

let array1 = ["item1", "item2"];
// let array2 = ["item1", "item2"];
// let array2 = array1.slice(0).concat(["item3", "item4"]);
// let array2 = [].concat(array1,["item3", "item4"]);
// new way 
// spread operator
let oneMoreArray = ["item3", "item4"]
let array2 = [...array1, ...oneMoreArray];

array1.push("item3");

console.log(array1===array2);
console.log(array1)
console.log(array2)

// for loop in array 

let fruits = ["apple", "mango", "grapes", "banana"];

// for(let i=0; i<=9;i++){
//     console.log(i);
// }

// console.log(fruits.length);
// console.log(fruits[fruits.length-2]);
let fruits2 = [];
for(let i=0; i < fruits.length; i++){
    fruits2.push(fruits[i].toUpperCase());
}

console.log(fruits2);


// while loop in array 

const fruits = ["apple", "mango", "grapes"];
const fruits2 = [];
let i = 0;
while(i<fruits.length){
    fruits2.push(fruits[i].toUpperCase());
    i++;
}
console.log(fruits2);

// for of loop in array
const fruits = ["apple", "mango", "grapes", "fruit4", "fruit5"];
const fruits2 = [];

// for(let fruit of fruits){
//     fruits2.push(fruit.toUpperCase());
// }
// console.log(fruits2);

for(let i = 0; i<fruits.length; i++){
    console.log(fruits[i]);

    // for in loop in array
const fruits = ["apple", "mango", "grapes", "fruit4", "fruit5"];
const fruits2 = [];

for(let index in fruits){
    fruits2.push(fruits[index].toUpperCase());
}
console.log(fruits2);

// array destructuring 
const myArray = ["value1", "value2", "value3","value4"];
// let myvar1 = myArray[0];
// let myvar2 = myArray[1];
// console.log("value of myvar1", myvar1);
// console.log("value of myvar2", myvar2);
let [myvar1, myvar2, ...myNewArray] = myArray;
console.log("value of myvar1", myvar1);
console.log("value of myvar2", myvar2);
console.log(myNewArray);


// objects reference type  
// arrays are good but not sufficient 
// for real world data 
// objects store key value pairs 
// objects don't have index

// how to create objects 

// const person = {name:"Golu ",age:22};
const person = {
    firstName: "Vikram",
    lastName: "Singh",
    age: 22,
    hobbies: ["guitar", "sleeping", "listening music"]
}
console.log(person);

// how to access data from objects 
// console.log(person["firstName"]);
// console.log(person["age"]);
// console.log(person.hobbies);

// how to add key value pair to objects
person["person"] = "male";
console.log(person);

// difference between dot and bracket notaion
// const key = "email";
// const person = {
//     name: "harshit",
//     age: 22,
//     "person hobbies": ["guitar", "sleeping", "listening music"]

// }

// console.log(person["person hobbies"]);
// person[key] = "harshitvashisth@gmail.com";
// console.log(person);

// how to iterate object 
const person = {
    name: "harshit",
    age: 22,
    "person hobbies": ["guitar", "sleeping", "listening music"]
}

// for in loop 
// Object.keys 

// for(let key in person){
//     // console.log(`${key} : ${person[key]}`);
//     console.log(key," : " ,person[key]);
// }

// console.log(typeof (Object.keys(person)));
// const val = Array.isArray((Object.keys(person)));
// console.log(val);

// for(let key of Object.keys(person)){
//     console.log(person[key]);
// }

// computed properties

const key1 = "objkey1";
const key2 = "objkey2";

const value1 = "myvalue1";
const value2 = "myvalue2";

// const obj = {
//     objkey1 : "myvalue1",
//     objkey2 : "myvalue2",
// }

// const obj = {
//     [key1] : value1,
//     [key2] : value2
// }

const obj = {};

obj[key1] = value1;
obj[key2] = value2;
console.log(obj);

// spread operator
// const array1 = [1, 2, 3];
// const array2 = [5, 6, 7];

// // const newArray = [...array1, ...array2, 89, 69];
// const newArray = [..."123456789"];
// console.log(newArray);

// spread operator in objects
const obj1 = {
    key1: "value1",
    key2: "value2",
  };
  const obj2 = {
    key1: "valueUnique",
    key3: "value3",
    key4: "value4",
  };
  
  // const newObject = { ...obj2, ...obj1, key69: "value69" };
  // const newObject = { ...["item1", "item2"] };
  // const newObject = { ..."abcdefghijklmnopqrstuvwxyz" };
  // console.log(newObject);

  // object destructuring
const band = {
    bandName: "led zepplin",
    famousSong: "stairway to heaven",
    year: 1968,
    anotherFamousSong: "kashmir",
  };
  
  let { bandName, famousSong, ...restProps } = band;
  console.log(bandName);
  console.log(restProps);

  // objects inside array 
// very useful in real world applications

const users = [
    {userId: 1,firstName: 'harshit', gender: 'male'},
    {userId: 2,firstName: 'mohit', gender: 'male'},
    {userId: 3,firstName: 'nitish', gender: 'male'},
]
for(let user of users){
    console.log(user.firstName);
}

// nested destructuring 
const users = [
    {userId: 1,firstName: 'harshit', gender: 'male'},
    {userId: 2,firstName: 'mohit', gender: 'male'},
    {userId: 3,firstName: 'nitish', gender: 'male'},
]
const [{firstName: user1firstName, userId}, , {gender: user3gender}] = users;
console.log(user1firstName);
console.log(userId);
console.log(user3gender);

//  function   

function singHappyBirthday(){
    console.log("happy birthday to you ......");
}
function sumThreeNumbers(number1, number2, number3){
    return number1 + number2 + number3;
}
// isEven
// input : 1 number 
// output : true , false 
// function isEven(number){
//     return number % 2 === 0;
// }
// console.log(isEven(4));
// function 
// input : string 
// output: firstCharacter 
// function firstChar(anyString){
//     return anyString[0];
// }
// console.log(firstChar("zbc"));
// function 
// input : array, target (number)
// output: index of target if target present in array 
function findTarget(array, target){
    for(let i = 0; i<array.length; i++){
        if(array[i]===target){
            return i;
        }
    }
    return -1;
}
const myArray = [1,3,8,90]
const ans = findTarget(myArray, 4);
console.log(ans);

// function expression 
// function singHappyBirthday(){
//     console.log("happy birthday to you ......");
// }
const singHappyBirthday = function(){
    console.log("happy birthday to you ......");
}
// singHappyBirthday();
const sumThreeNumbers = function(number1, number2, number3){
    return number1 + number2 + number3;
}
const ans = sumThreeNumbers(2,3,4);
// console.log(ans);
// function isEven(number){
//     return number % 2 === 0;
// }
const isEven = function(number){
    return number % 2 === 0;
}
// console.log(isEven(2));
const firstChar = function(anyString){
    return anyString[0];
}
const findTarget = function(array, target){
    for(let i = 0; i<array.length; i++){
        if(array[i]===target){
            return i;
        }
    }
    return -1;
}


// arrow functions
// const singHappyBirthday = function(){
//     console.log("happy birthday to you ......");
// }
const singHappyBirthday = () => {
    console.log("happy birthday to you ......");
}
singHappyBirthday();
const sumThreeNumbers = (number1, number2, number3) => {
    return number1 + number2 + number3;
}
const ans = sumThreeNumbers(2,3,4);
console.log(ans);
// const isEven = function(number){
//     return number % 2 === 0;
// }
const isEven = number => number % 2 === 0;
console.log(isEven(4));
const firstChar = anyString => anyString[0];
console.log(firstChar("harshit"));
const findTarget = (array, target) => {
    for(let i = 0; i<array.length; i++){
        if(array[i]===target){
            return i;
        }
    }
    return -1;
}

// hoisting 
// hello();
// function hello(){
//     console.log("hello world");
// }
// console.log(hello);
// const hello = "hello world";
// console.log(hello);

// functions inside function 
function app(){
    const myFunc = () =>{
        console.log("hello from myFunc")
    }
    
    const addTwo = (num1, num2) =>{
        return num1 + num2;
    }
    const mul = (num1, num2) => num1* num2;
    console.log("inside app");
    myFunc();
    console.log(addTwo(2,3));
    console.log(mul(2,3));
}
app();


// lexical scope 
const myVar = "value1";
function myApp(){
    
    function myFunc(){
        // const myVar = "value59";
        const myFunc2 = () =>{
            console.log("inside myFunc", myVar);
        }
        myFunc2();
    }
    console.log(myVar);
    myFunc();
}
myApp();

// block scope vs function scope 
// let and const are block scope
// var is function scope 
// if(true){
//     var firstName = "Saurabh";
//     console.log(firstName);
// }
// console.log(firstName);
function myApp(){
    if(true){
        var firstName = "Saurabh";
        console.log(firstName);
    }
    if(true){
        console.log(firstName);
    }
    console.log(firstName);
}
myApp();

// default parameters 
// function addTwo(a,b){
//     if(typeof b ==="undefined"){
//         b = 0;
//     }
//     return a+b;
// }
function addTwo(a,b=0){
    return a+b;
}
const ans = addTwo(4, 8);
console.log(ans);

// rest parameters 
// function myFunc(a,b,...c){
//     console.log(`a is ${a}`);
//     console.log(`b is ${b}`);
//     console.log(`c is`, c);
// }
// myFunc(3,4,5,6,7,8,9);
function addAll(...numbers){
    let total = 0;
    for(let number of numbers){
        total = total + number;
    }
    return total;
}
const ans = addAll(4,5,4,2,10);
console.log(ans);

// param destructuring 
// object 
// react 
const person = {
    firstName: "Saurabh",
    gender: "male",
    age: 500
}
// function printDetails(obj){
//     console.log(obj.firstName);
//     console.log(obj.gender);
// }
function printDetails({firstName, gender, age}){
    console.log(firstName);
    console.log(gender);
    console.log(age);
}
printDetails(person);

// callback functions 
function myFunc2(name){
    console.log("inside my func 2")
    console.log(`your name is ${name}`);
}
function myFunc(callback){
    console.log("hello there I am a func and I can..")
    callback("pandey");
}
myFunc(myFunc2);

// function returning function 
function myFunc(){
    function hello(){
        return "hello world"
    }
    return hello;
}
const ans = myFunc();
console.log(ans());

const numbers = [4,2,5,8];
// function myFunc(number, index){
//     console.log(`index is ${index} number is ${number}`);
// }
// numbers.forEach(function(number,index){
//     console.log(`index is ${index} number is ${number}`);
// });
// numbers.forEach(function(number, index){
//     console.log(number*3, index);
// })
const users = [
    {firstName: "Shivam", age: 23},
    {firstName: "mohit", age: 21},
    {firstName: "nitish", age: 22},
    {firstName: "garima", age: 20},
]
// users.forEach(function(user){
//     console.log(user.firstName);
// });
// users.forEach((user, index)=>{
//     console.log(user.firstName, index);
// })
// for(let user of users){
//     console.log(user.firstName);
// }

// map method 
// const numbers = [3,4,6,1,8];
// const square = function(number){
//     return number*number;
// }
// const squareNumber = numbers.map((number, index)=>{
//     return index;
// });
// console.log(squareNumber);
const users = [
    {firstName: "shivam", age: 23},
    {firstName: "mohit", age: 21},
    {firstName: "nitish", age: 22},
    {firstName: "garima", age: 20},
]
const userNames = users.map((user)=>{
    return user.firstName;
});
console.log(userNames);

// filter method 
const numbers = [1,3,2,6,4,8];
const evenNumbers = numbers.filter((number)=>{
    return number % 2 === 0;
});
console.log(evenNumbers);

// reduce 
const numbers = [1,2,3,4,5, 10];
// aim : sum of all the numbers in array 
// const sum = numbers.reduce((accumulator, currentValue)=>{
//     return accumulator + currentValue;
// }, 100);
// console.log(sum);
// accumulator , currentValue,  return 
// 1               2              3 
// 3               3              6
// 6               4              10
// 10              5              15
// 15              10             25
// const userCart = [
//     {productId: 1, productName: "mobile", price: 12000},
//     {productId: 2, productName: "laptop", price: 22000},
//     {productId: 3, productName: "tv", price: 15000},
// ]
// const totalAmount = userCart.reduce((totalPrice, currentProduct)=>{
//     return totalPrice + currentProduct.price;
// }, 0)
// console.log(totalAmount);
// total price      currentValue     return 
// 0                {}                  12000
// 12000            22000                34000
// 34000            15000                49000

// sort method 
// ASCII TABLE 
//char : ascii value
// '0' : 48
// '1' : 49
// '2' : 50
// '3' : 51
// '4' : 52
// '5' : 53
// '6' : 54
// '7' : 55
// '8' : 56
// '9' : 57
// ':' : 58
// ';' : 59
// '<' : 60
// '=' : 61
// '>' : 62
// '?' : 63
// '@' : 64
// 'A' : 65
// 'B' : 66
// 'C' : 67
// 'D' : 68
// 'E' : 69
// 'F' : 70
// 'G' : 71
// 'H' : 72
// 'I' : 73
// 'J' : 74
// 'K' : 75
// 'L' : 76
// 'M' : 77
// 'N' : 78
// 'O' : 79
// 'P' : 80
// 'Q' : 81
// 'R' : 82
// 'S' : 83
// 'T' : 84
// 'U' : 85
// 'V' : 86
// 'W' : 87
// 'X' : 88
// 'Y' : 89
// 'Z' : 90
// '[' : 91
// '\' : 92
// ']' : 93
// '^' : 94
// '_' : 95
// '`' : 96
// 'a' : 97
// 'b' : 98
// 'c' : 99
// 'd' : 100
// 'e' : 101
// 'f' : 102
// 'g' : 103
// 'h' : 104
// 'i' : 105
// 'j' : 106
// 'k' : 107
// 'l' : 108
// 'm' : 109
// 'n' : 110
// 'o' : 111
// 'p' : 112
// 'q' : 113
// 'r' : 114
// 's' : 115
// 't' : 116
// 'u' : 117
// 'v' : 118
// 'w' : 119
// 'x' : 120
// 'y' : 121
// 'z' : 122
// '{' : 123
// '|' : 124
// '}' : 125
// sort  
// 5,9,1200, 400, 3000
// 5, 9, 400, 1200, 3000 (expected)
// ["5", "9", "1210", "410", "3000"] 
// [53, 57, 49, 52, 51]
// const userNames = ['shivam', 'abcd', 'mohit', 'nitish', 'aabc', 'ABC', 'Harshit'];
// userNames.sort();
// console.log(userNames);
// const numbers = [5,9,1200, 410, 3000];
// numbers.sort((a,b)=>{
//     return b-a;
// });
// numbers.sort((a,b)=>a-b);
// console.log(numbers);
// 1200,410 
// a-b ---> 790
// a-b ---> postive (greater than 0) ---> b, a
// 410 , 1200
// a-b ---> negative ----> a,b
// 5, 9 ---> -4 
// price lowToHigh HighToLow 
const products = [
    {productId: 1, produceName: "p1",price: 300 },
    {productId: 2, produceName: "p2",price: 3000 },
    {productId: 3, produceName: "p3",price: 200 },
    {productId: 4, produceName: "p4",price: 8000 },
    {productId: 5, produceName: "p5",price: 500 },
]
// lowToHigh
const lowToHigh = products.slice(0).sort((a,b)=>{
    return a.price-b.price
});
const highToLow = products.slice(0).sort((a,b)=>{
    return b.price-a.price;
});
const users = [
    {firstName: "shivam", age: 23},
    {firstName: "mohit", age: 21},
    {firstName: "nitish", age: 22},
    {firstName: "garima", age: 20},
]
users.sort((a,b)=>{
    if(a.firstName > b.firstName){
        return 1;
    }else{
        return -1;
    }
});
console.log(users);


// find method 
// const myArray = ["Hello", "catt", "dog", "lion"];
// function isLength3(string){
//     return string.length === 3;
// }
// const ans = myArray.find((string)=>string.length===3);
// console.log(ans);
const users = [
    {userId : 1, userName: "shivam"},
    {userId : 2, userName: "harsh"},
    {userId : 3, userName: "nitish"},
    {userId : 4, userName: "mohit"},
    {userId : 5, userName: "aaditya"},
];
const myUser = users.find((user)=>user.userId===3);
console.log(myUser);

// every method
// const numbers = [2,4,6,9,10];
// const ans = numbers.every((number)=>number%2===0);
// console.log(ans);
const userCart = [
    {productId: 1, productName: "mobile", price: 12000},
    {productId: 2, productName: "laptop", price: 22000},
    {productId: 3, productName: "tv", price: 35000},
]
const ans = userCart.every((cartItem)=>cartItem.price < 30000);
console.log(ans);

// some method 
const numbers = [3,5,11,9];
// kya ek bhi number esa hai jo even hai 
// true 
// const ans = numbers.some((number)=>number%2===0);
// console.log(ans);
const userCart = [
    {productId: 1, productName: "mobile", price: 12000},
    {productId: 2, productName: "laptop", price: 22000},
    {productId: 3, productName: "tv", price: 35000},
    {productId: 3, productName: "macbook", price: 25000},
]
const ans = userCart.some((cartItem)=>cartItem.price > 100000);
console.log(ans);

// fill method 
// value , start , end 
// const myArray = new Array(10).fill(0);
// console.log(myArray);
const myArray = [1,2,3,4,5,6,7,8];
myArray.fill(0,2,5);
console.log(myArray);

// splice method 
// start , delete , insert 
const myArray = ['item1', 'item2', 'item3'];
// delete
// const deletedItem = myArray.splice(1, 2);
// console.log("delted item", deletedItem);
// insert 
// myArray.splice(1, 0,'inserted item');
// insert and delete 
const deletedItem = myArray.splice(1, 2, "inserted item1", "inserted item2")
console.log("delted item", deletedItem);
console.log(myArray);

// iterables 
// jispe hum for of loop laga sakein
// string , array are iterable 

// const firstName = "Yazhain";
// for(let char of firstName){
//     console.log(char);
// }

const items = ['item1', 'item2', 'item3'];
// for(let item of items){
//     console.log(item);
// }

// array like object 
// jinke pas length property hoti hai 
// aur jiko hum index se access kar sakte hai
// example :- string 

// const firstName = "Yazhain";
// console.log(firstName.length);
// console.log(firstName[2]);

// Sets (it is iterable)
// store data  
// sets also have its own methods
// No index-based access 
// Order is not guaranteed
// unique items only (no duplicates allowed)
// const items = ['item1', 'item2', 'item3'];
// const numbers = new Set();
// numbers.add(1);
// numbers.add(2);
// numbers.add(3);
// numbers.add(4);
// numbers.add(5);
// numbers.add(6);
// numbers.add(items);
// if(numbers.has(1)){
//     console.log("1 is present")
// }else{
//     console.log("1 is not present")
// }
// for(let number of numbers){
//     console.log(number);
// }
// const myArray = [1,2,4,4,5,6,5,6];
// const uniqueElements = new Set(myArray);
// let length = 0;
// for(let element of uniqueElements){
//     length++;
// }

// console.log(length);

// Maps
// map is an iterable

// store data in ordered fashion

// store key value pair (like object)
// duplicate keys are not allowed like objects


// different between maps and objects

// objects can only have string or symbol
// as key 

// in maps you can use anything as key
// like array, number, string 

// object literal 
// key -> string 
// key -> symbol
// const person = {
//     firstName : "Pranjal",
//     age: 7,
//     1:"one"
// }
// // console.log(person.firstName);
// // console.log(person["firstName"]);
// // console.log(person[1]);
// for(let key in person){
//     console.log(typeof key);
// }

// key value pair 
// const person = new Map();
// person.set('firstName', 'Saurabh');
// person.set('age', 7);
// person.set(1,'one');
// person.set([1,2,3],'onetwothree');
// person.set({1: 'one'},'onetwothree');
// console.log(person);
// console.log(person.get(1));
// for(let key of person.keys()){
//     console.log(key, typeof key);
// }
// for(let [key, value] of person){
//     // console.log(Array.isArray(key));
//     console.log(key, value)
// }

const person1 = {
    id: 1,
    firstName: "Rishabh"
}
const person2 = {
    id: 2,
    firstName: "Rishabh"
}

const extraInfo = new Map();
extraInfo.set(person1, {age: 8, gender: "male"});
extraInfo.set(person2, {age: 9, gender: "female"});
// console.log(userInfo);
console.log(person1.id);
console.log(extraInfo.get(person1).gender);
console.log(extraInfo.get(person2).gender)

// clone using Object.assign 

// memory  

const obj = {
    key1: "value1",
    key2: "value2"
}

// const obj2 = {'key69': "value69",...obj};
// const obj2 = Object.assign({'key69': "value69"}, obj);
// obj.key3 = "value3";
// console.log(obj);
// console.log(obj2);

// optional chaining 

const user  = {
    firstName: "Shivam",
    // address: {houseNumber: '1234'}
}



console.log(user?.firstName);
console.log(user?.address?.houseNumber);

// methods
// function inside object

function personInfo(){
    console.log(`person name is ${this.firstName} and age is ${this.age}`);
}

const person1 = {
    firstName : "Rohit",
    age: 8,
    about: personInfo
}
const person2 = {
    firstName : "mohit",
    age: 18,
    about: personInfo
}
const person3 = {
    firstName : "nitin",
    age: 17,
    about: personInfo
}

person1.about();
person2.about();
person3.about();

// console.log(window);
// "use strict";
// function myFunc(){

//     console.log(this);
// }
// myFunc();

function about(hobby, favMusician){
    console.log(this.firstName, this.age, hobby, favMusician);
}
const user1 = {
    firstName : "Rohit",
    age: 8,   
}
const user2 = {
    firstName : "mohit",
    age: 9,

}

// apply
// about.apply(user1, ["guitar", "bach"]);
// const func = about.bind(user2, "guitar", "bach");
// func();

const user1 = {
    firstName : "Pranjal",
    age: 8,
    about: function(){
        console.log(this.firstName, this.age);
    }   
}

// don't do this mistake 

// user1.about();
const myFunc = user1.about.bind(user1);
myFunc();

// arrow functions 

const user1 = {
    firstName : "pranjal",
    age: 8,
    about: () => {
        console.log(this.firstName, this.age);
    }   
}

user1.about(user1);

// const user1 = {
//     firstName : "Vivek",
//     age: 8,
//     about: function(){
//         console.log(this.firstName, this.age);
//     }   
// }

// const user1 = {
//     firstName : "Hello",
//     age: 8,
//     about(){
//         console.log(this.firstName, this.age);
//     }   
// }



user1.about();


// function (that function create object)
// 2.) add key value pair 
// 3.) object ko return krega 
function createUser(firstName, lastName, email, age, address){
    const user = {};
    user.firstName = firstName;
    user.lastName = lastName;
    user.email = email;
    user.age = age;
    user.address = address;
    user.about = function(){
        return `${this.firstName} is ${this.age} years old.`;
    };
    user.is18 =  function(){
        return this.age >= 18;
    }
    return user;
}

const user1 = createUser('Saurabh', 'Pandey', 'saurabh@gmail.com', 19, "my address");
console.log(user1);
const is18 = user1.is18();
const about = user1.about();
console.log(about);


// 


const userMethods = {
    about : function(){
        return `${this.firstName} is ${this.age} years old.`;
    },
    is18 : function(){
        return this.age >= 18;
    }
}
function createUser(firstName, lastName, email, age, address){
    const user = {};
    user.firstName = firstName;
    user.lastName = lastName;
    user.email = email;
    user.age = age;
    user.address = address;
    user.about = userMethods.about;
    user.is18 = userMethods.is18;
    return user;
}


const user1 = createUser('Saurabh', 'Pandey', 'saurabh@gmail.com', 19, "my address");
console.log(user1.about()); 


const obj1 = {
    key1: "value1",
    key2: "value2"
}

// __proto__

// offical ecmascript documentation 

// [[prototype]]

// __proto__ , [[prototype]]



// prototype    

const obj2 = Object.create(obj1); // {}
// there is one more way to create empty object
obj2.key3 = "value3";
// obj2.key2 = "unique";
console.log(obj2);

console.log(obj2.__proto__);

const userMethods = {
    about : function(){
        return `${this.firstName} is ${this.age} years old.`;
    },
    is18 : function(){
        return this.age >= 18;
    },
    sing: function(){
        return 'toon na na na la la ';
    }
}
function createUser(firstName, lastName, email, age, address){
    const user = Object.create(userMethods);// {}
    user.firstName = firstName;
    user.lastName = lastName;
    user.email = email;
    user.age = age;
    user.address = address;
    return user;
}


const user3 = createUser('mohit', 'ved', 'mohit@gmail.com', 17, "my address");
console.log(user3);
console.log(user3.about());
// console.log(user3.sing());


function hello(){
    console.log("hello world");
}

// javascript function ===> function  + object

// console.log(hello.name);

// you can add your own properties 
// hello.myOwnProperty = "very unique value";
// console.log(hello.myOwnProperty);

// name property ---> tells function name;

// function provides more usefull properties.


// console.log(hello.prototype); // {}

// only functions provide prototype property

// hello.prototype.abc = "abc";
// hello.prototype.xyz = "xyz";
// hello.prototype.sing = function(){
//     return "lalalla";
// };
// console.log(hello.prototype.sing()); 


// const userMethods = {
//     about : function(){
//         return `${this.firstName} is ${this.age} years old.`;
//     },
//     is18 : function(){
//         return this.age >= 18;
//     },
//     sing: function(){
//         return 'toon na na na la la ';
//     }
// }
function createUser(firstName, lastName, email, age, address){
    const user = Object.create(createUser.prototype);// {}
    user.firstName = firstName;
    user.lastName = lastName;
    user.email = email;
    user.age = age;
    user.address = address;
    return user;
}
createUser.prototype.about = function(){
    return `${this.firstName} is ${this.age} years old.`;
};
createUser.prototype.is18 = function (){
    return this.age >= 18; 
}
createUser.prototype.sing = function (){
    return "la la la la ";
}



const user3 = createUser('mohit', 'ved', 'jbnt@gmail.com', 17, "my address");
console.log(user3);
console.log(user1.is18());


// new keyword 
// 1.) this = {}
// 2.) return {} 
//

// __proto__ 
// // official ecmascript document
// [[prototype]]

// constructor function 
function CreateUser(firstName, lastName, email, age, address){
    this.firstName = firstName;
    this.lastName = lastName;
    this.email = email;
    this.age = age;
    this.address = address;
}
CreateUser.prototype.about = function(){
    return `${this.firstName} is ${this.age} years old.`;
};
CreateUser.prototype.is18 = function (){
    return this.age >= 18; 
}
CreateUser.prototype.sing = function (){
    return "la la la la ";
}

const user3 = new CreateUser('mohit', 'ved', 'jbnt@gmail.com', 17, "my address");
console.log(user3);
console.log(user1.is18());


function CreateUser(firstName, lastName, email, age, address){
    this.firstName = firstName;
    this.lastName = lastName;
    this.email = email;
    this.age = age;
    this.address = address;
}
CreateUser.prototype.about = function(){
    return `${this.firstName} is ${this.age} years old.`;
};
CreateUser.prototype.is18 = function (){
    return this.age >= 18; 
}
CreateUser.prototype.sing = function (){
    return "la la la la ";
}



const user3 = new CreateUser('mohit', 'ved', 'mohit@gmail.com', 17, "my address");

for(let key in user3){
    // console.log(key);
    if(user1.hasOwnProperty(key)){
        console.log(key);
    }

}

// let numbers = [1,2,3];

// // console.log(Object.getPrototypeOf(numbers));
// console.log(Array.prototype);
// console.log(numbers);

// function hello(){
//     console.log("hello");
// }



//    class 

class CreateUser{
    constructor(firstName, lastName, email, age, address){
        this.firstName = firstName;
        this.lastName = lastName;
        this.email = email;
        this.age = age;
        this.address = address;
    }
    about(){
        return `${this.firstName} is ${this.age} years old.`;
    }
    is18(){
        return this.age >= 18;
    }
    sing(){
        return "la la la la ";
    }
}
const user1 = new CreateUser('Saurabh', 'pandey', 'saurabh@gmail.com', 18, "my address");
const user2 = new CreateUser('Shivam', 'pandey', 'saurabh@gmail.com', 15, "my address");


class Animal {
    constructor(name, age){
        this.name = name;
        this.age = age;
    }
    eat(){
        return `${this.name} is eating`;
    }
    isSuperCute(){
        return this.age <= 1;
    }
    isCute(){
        return true;
    }
}
class Dog extends Animal{
    
} 
const tommy = new Dog("tommy", 3);
console.log(tommy);
console.log(tommy.isCute());  

// super 
class Animal {
    constructor(name, age){
        this.name = name;
        this.age = age;
    }
    eat(){
        return `${this.name} is eating`;
    }
    isSuperCute(){
        return this.age <= 1;
    }
    isCute(){
        return true;
    }
}
class Dog extends Animal{
    constructor(name, age, speed){
        super(name,age);
        this.speed = speed;
    }
    run(){
        return `${this.name} is running at ${this.speed}kmph`
    }
} 

const tommy = new Dog("tommy", 3,45);
console.log(tommy.run());



// same method in subclass
class Animal {
    constructor(name, age){
        this.name = name;
        this.age = age;
    }
    eat(){
        return `${this.name} is eating`;
    }
    isSuperCute(){
        return this.age <= 1;
    }
    isCute(){
        return true;
    }
}
class Dog extends Animal{
    constructor(name, age, speed){
        super(name,age);
        this.speed = speed;
    }
    eat(){
        return `Modified Eat : ${this.name} is eating`
    }
    run(){
        return `${this.name} is running at ${this.speed}kmph`
    }
} 
 
// const tommy = new Dog("tommy", 3,45);
// console.log(tommy.run());
// console.log(tommy.eat());
const animal1 = new Animal('sheru', 2);
console.log(animal1.eat());

// getter and setters 
class Person{
    constructor(firstName, lastName, age){
        this.firstName = firstName;
        this.lastName = lastName;
        this.age = age;
    }
    get fullName(){
        return `${this.firstName} ${this.lastName}`
    }
    set fullName(fullName){
        const [firstName, lastName] = fullName.split(" ");
        this.firstName = firstName;
        this.lastName = lastName;
    }
}
const person1 = new Person("Saurabh", "Pandey", 5);
// console.log(person1.fullName());
// console.log(person1.fullName);
// person1.fullName = "Saurabh Pandey";
// console.log(person1);


// static methods and properties


class Person{
    constructor(firstName, lastName, age){
        this.firstName = firstName;
        this.lastName = lastName;
        this.age = age;
    }
    static classInfo(){
        return 'this is person class';
    }
    static desc = "static property";
    get fullName(){
        return `${this.firstName} ${this.lastName}`
    }
    set fullName(fullName){
        const [firstName, lastName] = fullName.split(" ");
        this.firstName = firstName;
        this.lastName = lastName;
    }
    eat(){
        return `${this.firstName} is eating`;
    }
    isSuperCute(){
        return this.age <= 1;
    }
    isCute(){
        return true;
    }
}
const person1 = new Person("Saurabh ", "Pandey", 8);
// // console.log(person1.eat());
// const info = Person.classInfo();
// console.log(person1.desc);
// console.log(info);