Understanding the html document object model, Programming Languages

At the core of DHTML is the Document Object Model, or DOM, which represents the HTML or XML of a Web page that is displayed in a browser. The Document Object Model that represents HTML content is referred to as the HTML DOM, and the Document Object Model that represents XML content is referred to as the XML DOM. Throughout this book, you have created Web pages that conform to XHTML. Because XHTML documents are just another type of XML document, you can manipulate them with both the HTML DOM and the XML DOM. But which is preferable?

The W3C formally recommends using the XML DOM instead of the HTML DOM. Nonetheless, it's easier to use the HTML DOM with basic types of DHTML techniques, such as those discussed in this and the next chapter. Keep in mind, however, that you must use the XML DOM when using some advanced JavaScript techniques, such as AJAX, which is discussed in Chapter 12.

Each element on a Web page is represented in the HTML DOM by its own object. The fact that each element is an object makes it possible for a JavaScript program to access individual elements on a Web page and change them individually, without having to reload the page from the server.

Although the individual technologies that make up DHTML have been accepted standards for some time, the implementation of DHTML has evolved slowly. One of the main delays in implementation has to do with the DOM. Earlier versions of Internet Explorer and Navigator included DOMs that were almost completely incompatible with each other. This meant that you needed to write different JavaScript code sections for different browsers. At the time of this writing, Mozillabased Web browsers including Firefox, Internet Explorer 5.0 and higher, and Netscape 6 and higher are all compatible with a standardized version of the DOM, Level 3, that is recommended by the World Wide Web Consortium (W3C).

When it comes to Web page authoring, the most important part of the HTML DOM is the Document object. Through the Document object you can access other objects that represent elements on a Web page. Throughout this book, you have used the HTML DOM to access and manipulate form elements. Similarly, you can use JavaScript to manipulate the images on a Web page through the Image object. The value you assign to an element's name attribute becomes the name of an associated Image object. In order to access an Image object named companyLogo, you must append the image name to the Document object as follows: document.companyLogo. (You will learn how to work with the Image object in the next section.)

Posted Date: 2/26/2013 4:52:26 AM | Location : United States







Related Discussions:- Understanding the html document object model, Assignment Help, Ask Question on Understanding the html document object model, Get Answer, Expert's Help, Understanding the html document object model Discussions

Write discussion on Understanding the html document object model
Your posts are moderated
Related Questions
Write a function drawCA(aname, coords) that uses the plot3 command to draw the C α backbone of the protein. When calling this function, you should pass in the aname and coords var


You will create a simple network management configuration which checks that certain programs are running on your network and are performing as expected, and that certain system det

Write a program to use a robot to move the stack of blocks from a source location to a target location, based. Movement of robot arms, picking and dropping, can be controlled usi

Exception handling Exception handling is a mechanism that separates code that detects and handles exceptional circumstances from the rest of your program. Note that an exceptional

Windows Workflow Foundation Microsoft windows Work-flows foundation (WF) is an Enthusiasm technological innovation that provides an API, an in-process workflow website, and a rehos

I am getting error at business layer object in code behind page.

Shemrock Inc. is a brake pad manufacturing company. This company uses raw materials, such as carbon powder, iron, ash, and resin. It wants to develop an inventory management system

Produce a hierarchy chart, a structured flowchart, and a Pascal program (with appropriate comments) to generate the Sales Commission Report shown below. The commission for each sal

Programming Project Specification: IRC or Internet Relay Chat is an application that lets multiple users communicate via text messages with each other in common "virtual" rooms.