Section 4.1. The Object Constructor

4.1. The Object Constructor

Each JavaScript object is based on one object known as, appropriately enough, Object. Object is covered in Chapter 11, which goes into creating custom objects and libraries. JavaScript's approach to extensibility is a bit unusual. Though current versions of JS are not truly object-oriented, JavaScript does support the concept of a constructor and the ability to create instances of objects through the use of the new method.

All but one of the built-in objects have unique and useful methods and properties associated with the object type, some of which are accessible with object instances. Others are static, which means they're only accessible directly on the shared object.

The one object that doesn't have any unique properties or methods is the Boolean object. The only methods and properties it has are those associated with Object itself. I'll use it to demonstrate creating new instances of an object, and then move on to covering the other more complex objects.

To create a new instance of the Boolean object, use the new keyword and the following syntax:

var holdAnswer = new Boolean(true);

Once a Boolean is instantiated, you can access the primitive value it encapsulates (encloses) using another Object method, toValue:

if (holdAnwer.toValue) ...

You can also access it directly, as if it were a primitive data type:

if (holdAnswer) ...

If the Boolean object lacks new and exciting functionality, the other objects compensate for it.