// Explanation of var, let, and const

​

/*

var:

- With var, variable scope is function-scoped, meaning it is accessible anywhere within the function.

- Variables declared with var can be reassigned and reassigned within their scope.

*/

​

var myVar = "Hello";

myVar = "World";

console.log(myVar);  // Output: World

​

/*

let:

- With let, variable scope is block-scoped, meaning it is only accessible within the block it is declared.

- Variables declared with let can be reassigned within their scope.

*/

​

let myLet = "Hello";

myLet = "World";

console.log(myLet);  // Output: World

​

/*

const:

- With const, variable scope is block-scoped, just like let.

- However, variables declared with const cannot be reassigned.

- Once assigned, the value of a const variable can never be changed.

*/

​

const myConst = "Hello";

myConst = "World";  // This will cause an error because const variables cannot be reassigned.

Const vs Let vs Var

​

const pi = 3.14

​

pi = 1 

cannot do this becuase with const you cannot change the value

​

_____________________________________

​

​

Let --> is block level 

​

for(let i = 0; i < 3; i++) {

console.log(i) --> it will console here

}

console.log(i) ---> Not here

​

​

---------------------------------------

​

Var is for variables available to the entire function 

​

​

for(var j = 0; j < 3; j++) {

console.log(j) --> it will console here

}

console.log(j) ---> it will console here

            |                       |                    |

            |       VAR             |       LET          |        CONST

SCOPE       |   function, global    |    block scope     |     block scope

HOISTING    |   yes                 |    no              |     no

REASSIGN    |   yes                 |    yes             |     no

RE-DECLAIR  |   yes                 |    no              |     no

// Define, Update and Redefine:

// - You can define, update and redefine VAR

// - You can define and update LET but cannot redefine it

// - You can define CONST but cannot update or redefine it

​

// Scope:

// - LET & CONST are block scoped - anything within {} - same nesting level only

// - VAR is (so can LET & CONST be) function scoped - can be accessible within that function and cannot be used outside that function

Security level of Let, var and const ; Which one you have to use,,,

  var = less securty becuase it can be define another time in any scope { including function also },

  let = medium security because, let allows you to declare variables that are limited to the scope of a block statement, or expression on which it is used, unlike the var keyword, which declares a variable globally, or locally to an entire function regardless of block scope.

  const = high and ultra security because, const variables are unique in whole code

​

var greeter = "hey hi";

    function newFunction() {

        var hello = "hello";

    }

let greeting = "say Hi";

   let times = 4;

​

   if (times > 3) {

        let hello = "say Hello instead";

        console.log(hello);// "say Hello instead"

    }

   console.log(hello) // hello is not defined

var greeter = "hey hi";

    function newFunction() {

        var hello = "hello";

    }

var greeter = "hey hi";

    function newFunction() {

        var hello = "hello";

    }

var greeter = "hey hi";

    function newFunction() {

        var hello = "hello";

    }