A clear article about Ajax

1. Ajax (Asynchronous JavaScript and XML)

Ajax definition: allows the client browser to communicate with the server. ajax technology is used without refreshing the current page.

2. Without refreshing new pages, ajax, flash, javaApplet, Framework (iframe, frameset), and XMLHttpRequest technologies are used to communicate with servers.

Note: The Framework places multiple pages in the framework, which is a cross-page operation. It is different from the real non-click Page and server communication. Only refresh the page in a framework. The overall page is not refreshed.

3. The core of ajax is the javascript Object XMLHttpRequest.

4. ajax is not a new technology, but a combination of multiple technologies, including javascript, XHTML, CSS, DOM, XML, and XMLHttpRequest.

5. Ajax implementation steps:

1) Create an XMLHttpRequest object

2) establish a connection

3) Send request data to the server

4) the server responds to the client

There are also two if judgments to determine whether readyState is equal to 4, that is, the response is complete, and the status is equal to 200. That is, everything is normal.