travishen

function sayHiLater() {
  
  var greeting = 'Hi';
  
  // uses first-class function and create a function object on the flay by function expressions
  setTimeout(function() {
    console.log(greeting); // 30 sec later, it still have access to greeting variable
  }, 30000);

}

travishen

function callLater(callback) {
  
  console.log('Some work...');
  
  callback();
  
}

callLater(function() {

travishen

var person = {
  firstname: 'John',
  lastname: 'Doe',
  getFullName: function() {
    
    var fullname = this.firstname + ' ' + this.lastname;
    return fullname;
  
  }
}

travishen

/* No wraping */ 

var arr1 = [1, 2, 3];
var arr2 = [];
var limiter = 2;
arr1.forEach(function(item, i){
  arr2.push(item > 2);
});
console.log(arr2); // [false, false, true]

travishen

a === undefined; // Uncaught ReferenceError: a is not defined

var a;
a === undefined; // true

travishen

var person = {
  firstname: 'Default',
  lastname: 'Default',
  getFullName: function(){
    return this.firstname + ' ' + this.lastname;
  }
}

var john = {
  firstname: 'John',

travishen

var arr = [];
var obj = {};

console.log(arr.__proto__.constructor); // ƒ Array() { [native code] }
console.log(object.__proto__.constructor); // ƒ Object() { [native code] }

console.log(arr.__proto__.__proto__.constructor); // ƒ Object() { [native code] }
console.log(object.__proto__.__proto__); // null

travishen

function Person(firstname, lastname) {
  console.log('Invoke function: Person');
  this.firstname = firstname || 'Default';
  this.lastname = lastname || 'Default';
}

// JavaScript has no classes, use this syntax atract Java users 
var john = new Person('John', 'Doe');
console.log(john); 
// Invoke function: Person

travishen

function loadScript(scriptName, callback) {

   if (!jsArray[scriptName]) {
      var promise = jQuery.Deferred();

      // adding the script tag to the head as suggested before
      var body = document.getElementsByTagName('body')[0],
          script = document.createElement('script');
      script.type = 'text/javascript';
      script.src = scriptName;

travishen

function Person(firstname, lastname) {
  this.firstname = firstname || 'Default';
  this.lastname = lastname || 'Default';
}

var john = new Person('John', 'Doe');
console.log(john.__proto__.constructor === Person); // true

// .prototype
Person.prototype.getFullName = function() {