Learning JavaScript Design Patterns

A Brief Note on Classes

Keep in mind that there will be patterns in this table that reference the concept of “classes.” JavaScript is a classless language; however, classes can be simulated using functions.

The most common approach to achieving this is by defining a JavaScript function in which you then create an object using the new keyword. Use this to define new properties and methods for the object as follows:

// A Car "class"
function Car( model ) {

  this.model = model;
  this.color = "silver";
  this.year  = "2012";

  this.getInfo = function () {
    return this.model + " " + this.year;
  };

}

We can then instantiate the object using the car constructor we defined above like this:

var myCar = new Car("ford");

myCar.year = "2010";

console.log( myCar.getInfo() );

For more ways to define classes using JavaScript, see Stoyan Stefanov’s useful post on them.

Let us now proceed to review the table.

Table 8-1. 

Creational	Based on the concept of creating an object
Class
Factory method	Makes an instance of several derived classes based on interfaced data or events
Object
Abstract factory	Creates an instance of several families of classes without detailing concrete classes
Builder	Separates object construction from its representation; always creates the same type of object
Prototype	A fully initialized instance used for copying or cloning
Singleton	A class with only a single instance with global access points
Structural	Based on the idea of building blocks of objects ...