JavaScript Scopes & Hoisting

hoisting.js

/* Scopes  */ 

// Ex: 1
(function() {
   var a = b = 5;
})();
console.log(b); // 5, b is global without var. 

// Strict Mode
(function() {
   'use strict';
   var a = window.b = 5;
})();
console.log(b); // 5 , without window.b will throw an error.


var global = 10;
function changeGlobal(){
 alert(global);
 global = 20;
 alert(global);
}
changeGlobal();  // 10 20


/* Hoisting */ 

// Example 1 //
var global = 10;
function changeGlobal(){
 alert(global);
 var global = 20;
 alert(global);
}
alert(global)
changeGlobal();  // 10 undefined 20 


// After hoisting
var global = 10;
function changeGlobal(){
 var global;
 alert(global); // undefined
 global = 20;
 alert(global); // 20
}
alert(global);  // 10