script.js

console.log("Starting script.js");    // printing in console


// alert("Hello world!") // alert
// [1, 2].forEach(alert)   - it gives error because semicolun is not after one alert


/* it is a multiple
  lie cometns
  works*/

// alert("Hello world!") ;
// const resultPrommpt = prompt("What's Your Age",0) ;  // Prompt takes two values tile and default value
//     console.log(result) ;

// const result = confirm("Are you sure?") ;  // Confirm box if you click ok it returns true and if you click cancel it returns false 
// console.log(result) ;   


let name = "Hello world!"
var script = "script.js"  //block scpoe issue 
const lastName = "Doe"  //you can't change its' value

{
    let name = "Hello world!- block" //both name variable is diffrent
    var script = "script.js-new" // here it overwrites the value and it's same for whole file 
    // console.log(name,script,lastName) 
}
// console.log(name,script,lastName) //


// Data types
// console.log(9007199254740991 + 1); // 9007199254740992  - bigInt


// let dataTypes;
//     console.log(typeof dataTypes); // undefined
//     console.log(typeof 0); // number
//     console.log(typeof 10n); // bigint
//     console.log(typeof true); // boolean
//     console.log(typeof "hello"); // string
//     console.log(typeof Symbol("id")); // symbol
//     console.log(typeof Math); // object
//     console.log(typeof null); // object
//     // use typeof for identify datatypes


let str1 = "-1234            ";
str1 = Number(str1);
// console.log(str1); // -1234

let str = "123 4";
str = Number(str);
// console.log(str); // NaN

let booLean = true;
let booLean2 = false;
booLean = Number(booLean);
booLean2 = Number(booLean2);
// console.log(booLean,booLean2); // 1 0

let Null = null;
Null = Number(Null);
// console.log(Null); // 0

let Undefined;
Undefined = Number(Undefined);
// console.log(Undefined); // NaN

let valueOf = 123;
valueOf = String(valueOf);
// console.log(valueOf); // "123"

let valueOf2 = true;
valueOf2 = String(valueOf2);
// console.log(valueOf2); // "true"

let valueOf3 = null;
valueOf3 = String(valueOf3);
// console.log(valueOf3); // "null"



let valueOf4 = 123;
valueOf4 = Boolean(valueOf4);
// console.log(valueOf4); // true

let valueOf5 = 0;
valueOf5 = Boolean(valueOf5);
// console.log(valueOf5); // false

let valueOf6 = "hello";
valueOf6 = Boolean(valueOf6);
// console.log(valueOf6); // true

let valueOf7 = "";
valueOf7 = Boolean(valueOf7);
// console.log(valueOf7); // false


// console.log(typeof("hello"-3));
// console.log(typeof("hello"+3));

// "" + 1 + 0 = "10" // (1)
// "" - 1 + 0 = -1 // (2)
// true + false = 1
// 6 / "3" = 2
// "2" * "3" = 6
// 4 + 5 + "px" = "9px"
// "$" + 4 + 5 = "$45"
// "4" - 2 = 2
// "4px" - 2 = NaN
// "  -9  " + 5 = "  -9  5" // (3)
// "  -9  " - 5 = -14 // (4)
// null + 1 = 1 // (5)
// undefined + 1 = NaN // (6)
// " \t \n" - 2 = -2 // (7)


//comparision

// console.log(5 > 4); // true
// console.log("apple" == "pineapple"); // false
// console.log("2" > "12"); // true
// console.log(undefined == null); // true




// let age = prompt('age?', 18);
// if(age < 3){
//     console.log("Hi, baby!");
// } else if (age < 18){
//     console.log("Hello!");
// } else if (age < 100){
//     console.log("Greetings!");
// } else {
//     console.log("What an unusual age!");
// }

// let message = (age < 3) ? 'Hi, baby!' :
//   (age < 18) ? 'Hello!' :
//   (age < 100) ? 'Greetings!' :
//   'What an unusual age!';

// console.log( message + "using ? operator");


//Using the if..else construct, write the code which asks: ‘What is the “official” name of JavaScript?’

// If the visitor enters “ECMAScript”, then output “Right!”, otherwise – output: “You don’t know? ECMAScript!”

let officialName = prompt("What is the “official” name of JavaScript?","JS");
if(officialName == "ECMAScript"){
    console.log("Right!");
} else {
    console.log("You don’t know? ECMAScript!");
}

let Answer = (officialName == "ECMAScript") ? "Right!" : "You don’t know? ECMAScript!";
console.log(Answer + "using ? operator");