AJAX introduction
So you want to learn AJAX? You may already know HTML, CSS, or Javascript and you want to move on to something cooler, or you may have heard about AJAX and are curious about it, or one of many other reasons. Whatever your reason(s) may be, AJAX is a great to learn and know!
This lesson focuses on:
- What you should already know
- What is AJAX?
- What AJAX is not
- Support for AJAX
- AJAX in action
What you should already know
Before beginning your studies of AJAX, you should have at least a basic understanding of HTML/XHTML and Javascript. Since AJAX is a technology that makes usage of HTML/XHTML and Javascript, it is imperative to at least have a basic understanding of these subjects before learning AJAX.
Learn HTML in our HTML section.
Learn XHTML in our XHTML section.
Learn Javascript in our Javascript section.
What is AJAX?
AJAX stands for Asynchronous Javascript And XML. It is a web programming method made popular by Google in 2005 that allows the web developer to create more interactive web applications where the content on a page changes without actually reloading that page. Combining Javascript and HTTP requests, AJAX technology makes this possible.
The cornerstone of AJAX is the XMLHttpRequest object (covered in detail in the next lesson). It is this object that allows for AJAX to communicate with a web server and change the content on it without actually reloading that page and this eliminating the need for a submit button.
This is all achieved by using HTTP requests between a web browser and a web server that allow web pages to request small chunks of information from web servers as opposed to entire pages. Internet applications are consequently smaller, faster, and more user-friendly.
What AJAX is not
AJAX is not a separate language but rather it is a technology which combines elements of existing languages (XML, Javascript) to create a new web programming method to achieve certain means (changing the content on a page without reloading it).
Remember, AJAX is not a separate language!!
Support fot AJAX
AJAX is not supported the same way on all major browsers. Different browsers support AJAX differently.
For Internet Explorer, the ActiveXObject is used for AJAX, while for other browsers the XMLHttpRequest object is used for AJAX.
To learn about the support available in different browsers for AJAX in more detail, head on over to our AJAX browsers lesson.
AJAX in action
You can see AJAX in action at the following places:
Google Suggest
Google created their Google Suggest tool to instantly show the most popular results in a drop down style list as you type letters into a search box.
Visit Google Suggest
Del.icio.us
The popular bookmarking site del.icio.us uses AJAX in a similar way to Google Suggest. When you type a tag to associate with a bookmark, it will suggest a list of tags as you type.
Visit del.icio.us
Panic Goods
An online store that gets rather creative with AJAX. This site uses AJAX to allow the user to drag an item into a shopping cart which gets updated automatically.
Visit Panic Goods
