Notes.txt

Variables
Operators
Datatypes
Alert,prompt,confirm

Variables:- It is name given to memory location.
=> Var
=> Let
=> Const

var: 
It is keyword to declare Variables.
It can be Redeclare and Reassigned.
Ex:-
var a = 10;
a=20;//reassign
var a= 30;//redeclare
console.log(a);

Let:-
=> It is keyword to declare Variables.
=> It can be only Reassigned.
// Let Examples
let b = 10;
b=40; //reassign 
console.log(b);

Const:-
=> It is keyword to declare Variables.
=> It cannot be reassigned and redeclared.
Ex:-
const c = 10;
console.log(c);

Operators:-
=> Airthmetic Operators: +,-,*,/,%
=> Assignment Operators: =
=> Conditional Operators: <,>,<=,>=,!=,!==,==,===
=> Logical Operators: &, ||

Alert:-
alert("Click Ok to enter into the website")

Propmt:-
let result = prompt("Enter your Name ")
console.log(result)

Confirm:-
let result1 = confirm("Are you sure enter the website")
console.log(result1)

Datatypes:-
String, Number, Boolean,Array,Object,Bigninit,Symbol,Null,Undefined,Functions

Undefined:-
=> If a variable is declared but the value is not assigned,
then the value of that variable is undefined.
=> Then the datatype is also undefined.
Example:-
Let a;
console.log(a);

Null:-
=> Null is a special value that represents empty or unknown values.
=> The type of null will be an object.
=> It is a known bug in Javascript.
=> Javascript defines that null is equal to undefined.
Examples:-
Let num = null;
console.log(num)
console.log(typeof(num))

Object:-
=> Object is collection of properties.
=> Object are sturctured with key value pair.
=> Object do not have index.
syntax:
var/let/const objectname ={
    keyname:value
}

Examples:-
let person={
    firstname:"John",
    lastname:"Doe",
    age:35,
    Sex:"Male",
    phonenumber:9078563412,
    skills:["Javascipt","Html","CSS"]
}
console.log(person)