Technologies That Make Up Ajax
Ajax is, in itself, a combination of existing technologies. These include the following:
- XMLHttpRequest object
Let's briefly discuss each of them.
All the HTML elements in your web page are organized in a Document Object Model, a W3C recommendation that every browser follows. This model describes how all the elements in an HTML page, such as input fields, paragraphs, images, anchors, and so on, are related to the topmost structure: the "document." This model defines the structure in a tree consisting of all the attributes and methods defined for an object in the document.
CSS, or Cascading Style Sheets, are files that store the styles of your web page HTML elements. These files typically have the .css extension. Note that CSS is basically used to provide a customized look and feel to your HTML elements. You can use CSS files to store the formatting and style information of elements at a common place and then reuse it in your web forms to facilitate easy maintenance and enforce the consistency of the look and feel of the user interface elements.
As an example, you can store all the headings in all the web pages of an application by defining them as a class in the .css file. Later, if the heading style needs to be changed, you can do this just in one place—the .css file. The changes would be reflected across all web pages of your application wherever this class has been used.