Ajax PHP简单入门教程代码
首先我们来了解怎么在javascrīpt中创建这个对象:
var xmlHttp = new XMLHttpRequest();
这行简单的代码在 Mozilla、Firefox、Safari、Opera 以及基本上所有以任何形式或方式支持 Ajax 的非 Microsoft 浏览器中,创建了 XMLHttpRequest 对象。但是对于市场占有率达到70%的IE来说,这种方法是不行的,而不同的IE版本还有不同的创建方法,所以我们需要在IE下面使用下面两种创建对象的办法:
复制代码 代码如下:
try {
xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");//针对较新的浏览器
} catch (err) {
try {
xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");//针对较老的浏览器
} catch (err2) {
xmlHttp = false;
}
}
if (!xmlHttp){
alert("无法创建 XMLHttpRequest 对象!");
}
结合起来就是:
复制代码 代码如下:
var xmlHttp = false;
try {
xmlHttp = new XMLHttpRequest();
} catch (trymicrosoft) {
try {
xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
} catch (othermicrosoft) {
try {
xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
} catch (failed) {
xmlHttp = false;
}
}
}
if (!xmlHttp){
alert("无法创建 XMLHttpRequest 对象!");
}
然后,让我们建立一个函数getInfo(),打开异步请求:
复制代码 代码如下:
function getInfo() {
var num = document.getElementById("num").value;//获得表单的数据
var url = "/ajax/1.php?n=" + escape(num);
xmlHttp.open("GET", url, true);//这里的true代表是异步请求
}
xmlHttp.send(null);
在发送了数据之后,我们需要用回调方法来获得服务器的状态,所以就用到了onreadystatechange 属性。
xmlHttp.onreadystatechange = updatePage;
此语句已经要放在send()语句前面,这样才会有效,后面的updatePage是处理返回信息的一个函数。完整的getInfo()如下:
复制代码 代码如下:
function getInfo() {
var num = document.getElementById("num").value;//获得表单的数据
var url = "/ajax/1.php?n=" + escape(num);
xmlHttp.open("GET", url, true);//这里的true代表是异步请求
xmlHttp.onreadystatechange = updatePage;
xmlHttp.send(null);
}
我们还需要在html里面来触发这个函数:
下面我们需要来编写updatePage()这个函数:
function updatePage(){
if (xmlhttp.readyState == 4) {
var response = xmlhttp.responseText;
document.getElementById("city").value = response;
}
}
上面这段代码里面的readyState是服务器返回的一个状态,4这个状态表示请求已经发送,并处理完毕。responseText是获得服务器返回的信息,然后通过javascrīpt赋给ID为city的表单。
到此,一个简单的Ajax程序就完成了,完整的javascrīpt代码如下:
var xmlHttp = false;
try {
xmlHttp = new XMLHttpRequest();
} catch (trymicrosoft) {
try {
xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
} catch (othermicrosoft) {
try {
xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
} catch (failed) {
xmlHttp = false;
}
}
}
if (!xmlHttp){
alert("无法创建 XMLHttpRequest 对象!");
}
function getInfo() {
var num = document.getElementById("num").value;//获得表单的数据
var url = "/ajax/1.php?n=" + escape(num);
xmlHttp.open("GET", url, true);//这里的true代表是异步请求
xmlHttp.onreadystatechange = updatePage;
xmlHttp.send(null);
}
function updatePage(){
if (xmlhttp.readyState == 4) {
var response = xmlhttp.responseText;
document.getElementById("city").value = response;
}
}
这里还缺一个php文件,由于处理的方式不一样,写法也不一样,而且这不是Ajax的主要部分,所以这里就不放代码了。只要记住php是输出并返回所需要的数据就可以了。
好久没更新,今天看到这教程,对初学者挺适合.

Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Article

Hot Tools

Notepad++7.3.1
Easy-to-use and free code editor

SublimeText3 Chinese version
Chinese version, very easy to use

Zend Studio 13.0.1
Powerful PHP integrated development environment

Dreamweaver CS6
Visual web development tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

Hot Topics



PHP 8.4 brings several new features, security improvements, and performance improvements with healthy amounts of feature deprecations and removals. This guide explains how to install PHP 8.4 or upgrade to PHP 8.4 on Ubuntu, Debian, or their derivati

If you are an experienced PHP developer, you might have the feeling that you’ve been there and done that already.You have developed a significant number of applications, debugged millions of lines of code, and tweaked a bunch of scripts to achieve op

Visual Studio Code, also known as VS Code, is a free source code editor — or integrated development environment (IDE) — available for all major operating systems. With a large collection of extensions for many programming languages, VS Code can be c

JWT is an open standard based on JSON, used to securely transmit information between parties, mainly for identity authentication and information exchange. 1. JWT consists of three parts: Header, Payload and Signature. 2. The working principle of JWT includes three steps: generating JWT, verifying JWT and parsing Payload. 3. When using JWT for authentication in PHP, JWT can be generated and verified, and user role and permission information can be included in advanced usage. 4. Common errors include signature verification failure, token expiration, and payload oversized. Debugging skills include using debugging tools and logging. 5. Performance optimization and best practices include using appropriate signature algorithms, setting validity periods reasonably,

This tutorial demonstrates how to efficiently process XML documents using PHP. XML (eXtensible Markup Language) is a versatile text-based markup language designed for both human readability and machine parsing. It's commonly used for data storage an

A string is a sequence of characters, including letters, numbers, and symbols. This tutorial will learn how to calculate the number of vowels in a given string in PHP using different methods. The vowels in English are a, e, i, o, u, and they can be uppercase or lowercase. What is a vowel? Vowels are alphabetic characters that represent a specific pronunciation. There are five vowels in English, including uppercase and lowercase: a, e, i, o, u Example 1 Input: String = "Tutorialspoint" Output: 6 explain The vowels in the string "Tutorialspoint" are u, o, i, a, o, i. There are 6 yuan in total

Static binding (static::) implements late static binding (LSB) in PHP, allowing calling classes to be referenced in static contexts rather than defining classes. 1) The parsing process is performed at runtime, 2) Look up the call class in the inheritance relationship, 3) It may bring performance overhead.

What are the magic methods of PHP? PHP's magic methods include: 1.\_\_construct, used to initialize objects; 2.\_\_destruct, used to clean up resources; 3.\_\_call, handle non-existent method calls; 4.\_\_get, implement dynamic attribute access; 5.\_\_set, implement dynamic attribute settings. These methods are automatically called in certain situations, improving code flexibility and efficiency.
