variable.js

// variable are containers for data
//always gives a meanning full name for a variable.

// age is integer value
age = 19;   
console.log(age);

// fullname is work like a string
fullname="vaibhav gund";
console.log(fullname);


// null means i know this value but this variable is mt
x = null;
console.log(x);

// value is undefine it means i dont know what value in this 
y = undefined;
console.log(y);

// meannig full name like a following......

radius = 23;
console.log(radius);

salary = 34570;
console.log(salary);

height = 165.5;
console.log(height);


// boolean type = true / false

// example

isfollow = true;
console.log(isfollow);

isFollow = false;
console.log(isfollow);



// rule of variable //

//  variable name are case sensitive 'a' and 'A' is a different.

//  only letter, digits,underscore(_) and $ is allowed.(not even space)

// only letter ,underscore (_) or $ should be 1st character.

// reserved words cannot be variable names.




// keywords


// var  ======  variable can be re declared and updated .global scope variable. ....... .do not use

// let ===  variable cannot be re declared but can be updated a block scope variable. ....... . declare at onetime 

// const ==== variable cannot be re declared or updated a block scope variable........ . use mostly


//  let

let name = "vaibhav gund ";
console.log(name);

name ="kedarnath";


let fullName = "vaibhav bhausaheb gund";

let totalPrice = 100000;
console.log (totalPrice);


// let  and const are a block scope variable

{
    let a =40;
    a = 30;
    console.log(a);

}