Section 9.1. BOM at a Glance

9.1. BOM at a Glance

The BOM forms a hierarchy of objects, with each object at each level accessible via a parent object above it. All of the elements of the BOM are accessible via the window, which is the topmost element. The next level below features document, which we've used extensively. The level also contains the navigator, frames, location, history, and screen objects. From the document, several collections of objects are accessible: forms, anchors, links, and images. As demonstrated in Chapter 3, the form itself has elements, but we'll stop at just the top three levels in this chapter.

Figure 9-1 shows the BOM at a glance, and how all of these elements relate to each other.

Figure 9-1. Hierarchy of the Browser Object Model

As can be quickly seen, window is the top dog in this bunch. We'll look at it first.