AJAX教程02 AJAX Introduction（From w3schools）译读

What you should already know

Before you continue you should have a basic understanding of the following:

• HTML / XHTML
• JavaScript

If you want to study these subjects first, find the tutorials on our Home page.

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AJAX = Asynchronous JavaScript and XML

AJAX is not a new programming language, but a new technique for creating better, faster, and more interactive web applications.

With AJAX, a JavaScript can communicate directly with the server, with the XMLHttpRequest object. With this object, a JavaScript can trade data with a web server, without reloading the page.

AJAX uses asynchronous data transfer (HTTP requests) between the browser and the web server, allowing web pages to request small bits of information from the server instead of whole pages.

The AJAX technique makes Internet applications smaller, faster and more user-friendly.

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AJAX is based on Internet standards

AJAX is based on the following web standards:

• JavaScript
• XML
• HTML
• CSS

  AJAX applications are browser- and platform-independent.

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AJAX is about better Internet-applications

Internet-applications have many benefits over desktop applications; they can reach a larger audience, they are easier to install and support, and easier to develop.

However, Internet-applications are not always as "rich" and user-friendly as traditional desktop applications.

With AJAX, Internet applications can be made richer and more user-friendly.

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Start using AJAX today

There is nothing new to learn.

AJAX is based on existing standards. These standards have been used by developers for several years

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你应该已经掌握了这些知识：

• HTML / XHTML
• JavaScript

AJAX = 异步JavaScript与XML
AJAX并非一种新的编程语言，而是一种新的技术，这种技术可以帮助人们建立更好、更快、更富有交互性的Web程序。
采用了AJAX后，JavaScript采用XMLHttpRequest对象直接与服务器进行通讯。通过XMLHttpRequest对象，JavaScript可以与Web服务器进行数据交换，而非传统的通过页面的重新载入来完成此项工作。
AJAX在用户的浏览器和服务器之间采用了异步数据传输（通过HTTP请求），这种方式使得网页只需要传输更少的数据而不用重新载入整个页面。
AJAX技术使得互联网程序更简洁、更迅速、用户界面更友善。

AJAX基于这些网络标准：
AJAX基于以下这些Web标准

• JavaScript
• XML
• HTML
• CSS

采用AJAX技术的应用程序是基于浏览器的并且是平台无关的。

AJAX是为了构建更佳的互联网应用程序：
互联网应用程序吸取了很多桌面程序的经验，并可以为更多的用户提供服务，更便于在用户的电脑上进行安装、更易于程序员进行开发。
但是互联网应用程序在界面上更“弱”，用户界面不够友善。
但AJAX的横空出世却可以克服这些特点。


本文的英文网址：http://www.w3schools.com/Ajax/ajax_intro.asp