Javascript Hoisting

Javascript Hoisting is a mechanism that moves all variable and function declarations to the top of their scope before code execution. However, variable assignments still happen where they originally were.
Note:- variable declaration is hoisted while the assignment remains in the same place.

console.log(emp_name);
var emp_name = "John";

Note:- undefined means value is not defined in the variable.

Now, the javascript hoisting mechanism run the above code into 3 steps
step1:- firstly declare emp_name variable

var emp_name

step2:- Now run the console.log

console.log(emp_name);

step3:- Now defined the emp_name value

emp_name = "John";

var emp_name
console.log(emp_name);
emp_name = "John";

var emp_name; // → Hoisted variable declaration
console.log(emp_name); // → undefined
emp_name = "John"; // → variable assignment remains in the same place
console.log(emp_name); // → John

'use strict';
console.log(emp_name); 
emp_name = 'John'; 

function declarations are hoisted to the top of their scope.

display_name();
function display_name() {
  var emp_name='John'
    console.log('Hello '+emp_name);
}

Hosting process of the function of the above code

function display_name() {
  var emp_name='John'
    console.log('Hello '+emp_name);
}
display_name();

display_name();
var display_name= function() {
  var emp_name='John'
  console.log(emp_name);
}

Javascript Hoisting – Interview Questions

Javascript Hoisting – Objective Questions (MCQs)