Tham khảo sách 'javascript bible_ chapter 8', công nghệ thông tin, kỹ thuật lập trình phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Window and Document Objects Now that you have exposure to programming fundamentals it will be easier to demonstrate how to script document objects. Starting with this lesson the tutorial turns back to the document object model diving more deeply into each of the objects you will place in many of your documents. Document Objects As a refresher study the Netscape Navigator document object hierarchy in Figure 8-1. This lesson focuses on objects at or near the top of the hierarchy window location history and document. The goal is not only to equip you with the basics so you can script simple tasks but also to prepare you for in-depth examinations of each object and its properties methods and event handlers in Part III of this book. I introduce only the basic properties methods and event handlers for objects in this tutorial far more are to be found in Part III. Examples in that part of the book assume you know the programming fundamentals covered in previous lessons. The Window Object At the very top of the document object hierarchy is the window object. This object gains that exalted spot in the object food chain because it is the master container for all content you view in the Web browser. As long as a browser window is open even if no document is loaded in the window the window object is defined in the current model in memory. In This Chapter What the window object does How to access key window object properties and methods How to trigger script actions after a document loads The purposes of the location and history objects How the document object is created How to access key document object properties and methods 86 Part II JavaScript Tutorial Figure 8-1 The Netscape Navigator 4 document object model In addition to the content part of the window where documents go a window s sphere of influence includes the dimensions of the window and all of the stuff that surrounds the content area. Netscape calls this area where scrollbars toolbars the status bar and menu bar .
