CSS, DHTML, and Ajax, Fourth Edition

Despite appearances, setting up basic Ajax functionality is not that difficult. It involves three main parts: making the server call, having the server process the call, and then filtering the data that comes back. This can be as simple as grabbing a chunk of HTML code from the server to place on the current page, or as complex as submitting multiple variables to a database to update a 3D map of the earth. Let's start with the simple stuff.

In this chapter, you will learn how to do the following:

• Fetch content directly from the server and place it onto the current page

• Send data from the current page back to the server and get a response to place on the page

• Filter responses from the server for different situations

• Set up an external JavaScript library file to hold Ajax functions to be used across multiple Web pages

Let's get started with an overview of how Ajax code works by sending requests to the server.