Ajax Summary
Asynchronous JavaScript + XML, while not a technology in itself, is a term coined in 2005 by Jesse James Garrett, that describes a "new" approach to using a number of existing technologies together, including: HTML or XHTML, Cascading Style Sheets, JavaScript, The Document Object Model, XML, XSLT, and the XMLHttpRequest object. When these technologies are combined in the AJAX model, web applications are able to make quick, incremental updates to the user interface without reloading the entire browser page. This makes the application faster and more responsive to user actions.
How to build an Ajax website?
You need for some wrapper. A short list of frameworks is provided below.
Your JavaScript program, integrated into a web page, sends request to the
server to load files for rebuilding of pages. The received documents are processed
with Dom's methods or XML parsers and the data are used to update the pages.
- If JavaScript is not activated, Ajax can't works. The user must be asked
to set JavaScript from within options of the browser, with the "noscript"
tag.
- Since data to display are loaded dynamically, they are not part of the page,
and the keywords inside are not viewed by search engines.
- The asynchronous mode may change the page with delays (when the processing
on the server take some times), this may be disturbing.
- The back button may be deactivated (this is not the case in examples provided
here). This may be overcomed.
Ajax is based on these specifications:
- XML 1, HTML
4, DOM
2, CSS 2
from W3C
- ECMAScript
1.5. Standard for JavaScript from ECMA.
- W3C draft specification for XMLHttpRequest.
-
HTTP 1.1. Status codes: 404 etc