• Hoisting means accessing the variables and functions before their declaration.
• The var declarations and named functions are hoisted in JavaScript. We can access the variables even before their declaration, but the variable value is undefined.
• whereas named functions also access even before their declaration. You can invoke the function; it will always work, but print the function, and it will print the actual function code

console.log(name) //undefined
display() /hello
var name ="shivaji";

function display(){
	console.log("hello");
}

Example _2:

console.log(name) //undefined
display() //undefined
var name ="shivaji";

var display = function(){
	console.log(" hello ");
}

Note: The anonymous function and arrow function are treated as variables, which is why it will print undefined.

• Arrows and functions are treated as variables.
• let and const declarations are hoisted, but they are hoisted very differently from var. These are in the temporal dean zone.
• Memory is assigned for var declarations, and these variables are attached to the global object, but in case of let & const declarations, they are allocated memory but in a different location rather than global; we can not access let & const declarations before we have put some value in them.

var a=10;
let b=2000;
console.log(window.a) //10
console.log(window.b) //undefined //it will stored in seperate memory location

Rules :

Let: redeclaration is not possible in the same scope. It throws a syntax error, won't execute any line of code in our program

console.log("error") // not execute
var a=10;
let a=2000;

Var: redeclaration is possible in the same scope.

console.log("no error")
var a=10;
var a=2000;