JavaScript-Folder/DataType.html at main · researcher-program/JavaScript-Folder · GitHub

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<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title> Data Types & Its Conversion | JavaScript | Al- Arafat </title>
</head>
<body>
    <H1> Assalamualaikum Or-Rohmatullah </H1>
    <H2> Al -  Arafat </H2>
</body>
<script src="DataType.js"></script>
<script src="test-2.js"></script>
<script>
    // Type-1:

    /*
                ************** 1. DateType:  *************
                  Actually,Older "js" had not "Array,class,module" but Newer "js" have had this.
                This new Js has to refer as:
                                        "use Strict";
//Treat all js code as newer version.
*/
/*
alert( 3 + 3)
we are using node.js,not browser,that's why,node.js has not run as an "alert" command,but it fully accessable in browser ,but which isn't mean by  it can't use in node.js this "alert" command,but it use but, different way/syntax therefore can't run on nodejs.
*/

/*
let name = " Arafat " // string type
let age = 26 // number
let IsloggedIn = false // boolean type

let valueInNumber = Number
console.log("Arafat");
*/
/*
 ~ DataType:
 1.bigint ; 2.string => single quote {''} / {" "} double quote ;3.boolean =>true/false ; 4.null => standalone value ; 5.undefined ; 6.symbol =>Unique ; 7. number => 2 to power 53+ ; 8.object.

console.log(typeof "arafat"); //string
console.log(typeof age); //number
console.log(typeof null); //object
console.log(typeof undefined); //undefined
*/
/*
let score = "33"
console.log(typeof score);
console.log(typeof(score));
*/
/*
console.log(3
     +
     3);

Please stay out of code readability should be high
*/

/*
             ************** 2. DateType Conversion:  *************
             It means convert into data ,like: number --{convert}-->string,etc.

let score = "33abd" //NaN => Not a Number
 console.log(typeof score);
console.log(typeof(score)); //As a methods inside of "Parenthesis / Parentheses ==> ( )"

let valueInNumber = Number(score)
console.log(typeof valueInNumber);
console.log(typeof (valueInNumber));
*/
/*
let score1 = null //0
console.log(typeof score1);
console.log(typeof(score1));

let valueInNumber1 = Number(score1)
console.log(typeof valueInNumber1);
console.log(typeof (valueInNumber1));
*/
/*
let score2 = undefined //NaN => Not a Number
console.log(typeof score2);
console.log(typeof(score2));

let valueInNumber2 = Number(score2)
console.log(typeof valueInNumber2);
console.log(typeof valueInNumber2);

let score3 = True // True=1 / False=0
console.log(typeof score3);
console.log(typeof(score3));

let valueInNumber3 = Number(score3)
console.log(typeof valueInNumber3);
console.log(typeof valueInNumber3);

let score4 = "Arafat" //NaN => Not a Number
console.log(typeof score4);
console.log(typeof(score4));

let valueInNumber4 = Number(score4)
console.log(typeof valueInNumber4);
console.log(typeof valueInNumber4);
*/

/*
33 ==> 33{ Number};
"33"==>String;
3sfd==>NaN{Not a Number};
"3sfd"==>NaN{Not a Number};
True=1 / False=0
*/
/*
let isLoggedIn =1 // Output given is "True"
let isLoggedIn ="" // Output given is "False"
let isLoggedIn =" Arafat" // Output given is "True"

let booleanIsLoggedIn = Boolean(isLoggedIn )
console.log(booleanIsLoggedIn);
*/
/*
let someNumber = 33
let stringNumber = String(someNumber)
console.log(stringNumber); //output ==>33
console.log(typeof stringNumber); //convert into string
*/

</script>
<script>
    // Type-2:

                // Data Type :
// "use strict";
let name = " Al - Arafat " // string
console.log(typeof "Arafat");//string
console.log(typeof name);//string


let age = 18 // number {2 to power 53 or something}
let time = " 18 hour " // string
let isLoggedIn = true // boolean = true / false
let bigint =154874576444444449648444444471616944444 // bigint //SyntaxError: Octal literals are not allowed in strict mode.যদি "use strict " ব্যবহার করা হয় তবে bigint কাজ করে না,তাই "use strict " comment  করে রাখতে হল...।

console.log(typeof null); // Object
console.log(typeof undefined); //undefine

console.table([bigint, isLoggedIn,time,age,name]);

                // Data Type Conversion
let score = 33
console.log(typeof score);
console.log(typeof ( score));
let scores = " 33 "
console.log(typeof scores);
console.log(typeof ( scores));

  // but, now it's time to conversion of Data type :
 let valueInNumber = " 1534 "
  let valueOfNumber = Number( valueInNumber) // Note That : " 1534" was a string but " Number( valueInNumber)" this method is convert into number ,like : string ==> number.
console.log(typeof ( valueOfNumber ));

let subject = 14345
let subjects = String( subject )
console.log(subjects);
console.log(typeof ( subjects ));

// But, The Problem is :
let core = "33abc"
console.log(typeof core);
let cores = Number( core )
console.log(cores); // NaN =>Not a Number

// let null = null // SyntaxError: Unexpected token 'null'
let nulls = null
let nullism = Number( nulls )
console.log(nullism); // 0

// let undefined = undefined // ReferenceError: Cannot access 'undefined' before initialization
let undefine = undefined
let Unexpected = Number( undefine )
console.log(Unexpected); // NaN

// let boolean = true // 1
let boolean = false // 0
let booleans = Number( boolean )
console.log(booleans);

let Name = " Arafat"
let names = Number( Name )
console.log(names); // NaN

let empty = " "
let empties = Number( empty )
console.log(empties); // 0

// let log = 1 // true
//  let log = 2 // true
// let log = 0 // false
// let log = "" // false ...But,
// let log = " " // True { " <spaces>"}
let log = " arafat" //true
let logs = Boolean(log )
console.log(logs);

</script>
</html>