ajax1—php（27）

1 Introduction

Web program working principle diagram:

Traditional web program working principle diagram:

Ajax working principle diagram:

1. About Ajax

l Asynchronous

l JavaScript

l And

l XML

Ajax is a technology that uses javascript to interact with xml and the server

Xml:

Json:

2. Development history

l was born in 1998

l 2005 Popular

3. Running platform

l Google Chrome

l Mozilla

l Firefox

l Internet Explorer

l Opera

l Konqueror

l Safari

2. Core objects

XMLHttpRequest

1. Create objects

Under different browsers, the way to create ajax objects is slightly different.

Under IE:

new ActiveXObject("Microsoft.XMLHTTP")

w3c model browser:

new XMLHttpRequest()

5. Encapsulate ajax

Call code:

3. Ajax object related properties and methods:

1. Related methods:

l open(method,url)

Initialize ajax object

method: request method post, get

url: Request resource address

l setRequestHeader(header,value)

Set request header information

Header: header information

Value: value

l send(content)

Send a request

Content: The passed parameters need to be placed here only when making a post request

2. Related attributes:

l readyState

The status code of the Ajax object, this status code will change at any time

0: Indicates that the object has been created but not initialized

1: Indicates that the object has been initialized but not sent

2: The send method has been called to make a request

3: Receiving data (part of it received)

4: Reception completed

l onreadystatechange

The callback function triggered when the status code of the ajax object changes

l status

http response status code

l statusText

Text of http response

l responseText

Text of http response content

l responseXML

xml data of http response content

There are three main ways to transfer Ajax object data:

Text: responseText

Xml: responseXML

Json：responseText

The above introduces ajax1-php (27), including the relevant content. I hope it will be helpful to friends who are interested in PHP tutorials.