Explain Hoisting in javascript

 Hoisting is a default behaviour of javascript where all the variable and function declarations are moved on top.

This means that irrespective of where the variables and functions are declared, they are moved on top of the scope. The scope can be both local and global.

Example 1:

hoistedVariable = 3;
console.log(hoistedVariable); // outputs 3 even when the variable is declared after it is initialized	
var hoistedVariable;

Example 2:

hoistedFunction();  // Outputs " Hello world! " even when the function is declared after calling

function hoistedFunction(){ 
  console.log(" Hello world! ");
}

Example 3:

// Hoisting takes place in the local scope as well
function doSomething(){
  x = 33;
  console.log(x);
  var x;
}

doSomething(); // Outputs 33 since the local variable “x” is hoisted inside the local scope

**Note - Variable initializations are not hoisted, only variable declarations are hoisted:

var x;
console.log(x); // Outputs "undefined" since the initialization of "x" is not hoisted
x = 23;

**Note - To avoid hoisting, you can run javascript in strict mode by using “use strict” on top of the code:

"use strict";
x = 23; // Gives an error since 'x' is not declared
var x;