3D Game Programming

We won’t be creating visualizations in this chapter. Instead we’ll be creating

objects in ICE and looking at them in the JavaScript console. So be sure to

have the JavaScript console open.

17.2 Simple Objects

Programmers refer to things as objects. Anything that we can touch or talk

about in the real world can be described as an object in the computer world.

Consider movies, for instance. I think we can all agree that Star Wars is the

greatest movie of all time. Right? Well, here we describe Star Wars as a

JavaScript object:

varbest_movie = {

title:'Star Wars',

year: 1977

};

Even though it’s short, there’s a lot going on in that example. First of all, we

see that JavaScript has another use for curly braces other than just wrapping

function definitions and if statements. Curly braces can also wrap JavaScript

objects. Additionally, we see that JavaScript objects are just like numbers

and strings—they can be assigned to a variable (best_movie in this case).

More importantly, objects let us describe something in different ways. In this

case, we can describe a movie with a title, the movie’s director, and the year

in which the movie was made. The different pieces of information that we

might use to describe things are called attributes.

The attributes of an object can be anything. In our Star Wars example, the

attributes are strings and numbers. We could have used Booleans, lists, and

even functions.

varbest_movie = {

title:'Star Wars',

year: 1977,

stars: ['Mark Hamill','Harrison Ford','Carrie Fisher'],

aboutMe:function() {

console.log(this.title +', starring: ' + this.stars);

}

};

best_movie.aboutMe();

// => Star Wars, starring: Mark Hamill,Harrison Ford,Carrie Fisher

Calling the aboutMe() function on our best_movie objects will produce the “Star

Wars, starring...” message in the JavaScript console. This is what the

console.log() call does—it logs whatever we want to the JavaScript console.

Chapter 17. Project: Learning about JavaScript Objects • 160

Prepared exclusively for Michael Powell report erratum • discuss