View source for Head First into Unity with UnityScript

=== Lots More Types, Two Kinds of Array, No Object Syntax Sugar ===

JavaScript has, in essence, three types: number, string, and Object (with functions and arrays in essence being Objects). Unity's JavaScript has many more types, including:

Objects, which are NOT interchangeable with arrays, or Arrays (which are somewhat like JavaScript's objects, but not dynamic):
<syntaxhighlight lang="javascript">var a = new Object(); // works
a.fred = "wilma"; // runtime exception!</syntaxhighlight>

native arrays (which are not associative or dynamic):
<syntaxhighlight lang="javascript">var a = [1, 2, 3];
a.Push(4); // ERROR -- won't work!</syntaxhighlight>

If you want to make an array of a specific type:
<syntaxhighlight lang="javascript">public var friendsOfCarlotta : Transform[];</syntaxhighlight>

UnityScript Arrays (which are associative and dynamic):
<syntaxhighlight lang="javascript">var a = new Array();
a.Push(4); // This works</syntaxhighlight>

You can convert UnityScript Arrays to native arrays (which are faster but less flexible) using ToBuiltIn(ArrayType), e.g.:

<syntaxhighlight lang="javascript">var a = new Array();
a.Push(1);
a.Push(3.1415926535);
a.Push(17);
var b = a.ToBuiltin(float);</syntaxhighlight>

'''Integer types (including int, uint32, etc.)''':

Unity supports a large number of special case variations of the integer type. In general you'll know if you need them and don't need to worry otherwise.

'''Unity has many built-in classes (e.g. Vector3)''':

You'll become familiar with these as you work with Unity, in much the same way you become familiar with the DOM classes as you work with browsers. (Except Unity's classes suck much less than the DOM.)

One of the things that makes Unity a lot of fun to work with is that it uses a very liberal "mixin" strategy for classes. Usually you can "get at" the classes you need very quickly and easily. The most common example is the Transform class which quickly gets you to any associated class that's "attached" to the same object you're dealing with very quickly and easily.

E.g. in a typical behavior you'll have access to a variable named "transform" (referring to the instance of Transform associated with the object to which the behavior is attached). If you need the associated position (a Vector3) it's transform.position; if you need its GameObject it's transform.gameObject. If you need its renderer, it's transform.renderer. And so on. Generally, in Unity if you have one of an object's major properties you can quickly get at all its others.

a) Unity's String class lacks many of the nicer features of JavaScript's strings.

b) Unity's internal arrays are far less flexible than JavaScript's arrays or objects. However, various collection types such as List, Dictionary, Queue and so on are available. Internal arrays always have the advantage of the best speed.