PHP's cross-domain requests and Ajax technology bring a richer interactive experience to the website

PHP’s cross-domain request and Ajax technology bring a richer interactive experience to the website

With the rapid development of the Internet, the website serves as an important platform for information transmission and exchange. Platform, how to provide a better user experience has become the focus of attention. During the website development process, PHP's cross-domain requests and Ajax technology have become important means to achieve this goal. This article will introduce PHP's cross-domain requests and Ajax technology, and give code examples.

1. What is a cross-domain request?
Cross-domain request refers to an HTTP request initiated from one source (domain) to another source (domain) in the browser. For example, in the page of source A, sending a request to the server of source B through JavaScript code is a cross-domain request. Since cross-domain requests involve cross-domain security policies, browsers automatically block cross-domain requests by default.

2. Methods to solve cross-domain requests
In order to solve the problem of cross-domain requests, it can be achieved by setting it on the server side.

1. Using JSONP
   JSONP is a method of making cross-domain requests using GET requests with the <script> tag. Since the <script> tag has no cross-domain restrictions, you can implement cross-domain requests by creating a dynamic <script> tag. </script>

Sample code:

// 源A的页面
<script>
function callback(data) {
    // 处理返回的数据
}

var script = document.createElement('script');
script.src = 'http://b.com/data.php?callback=callback';
document.head.appendChild(script);
</script>

// 源B的服务器
<?php
$data = array('name' => 'John', 'age' => 30);
echo $_GET['callback'] . '(' . json_encode($data) . ')';
?>

2. Set the response header
   Set the response header on the server side to allow cross-domain access. By adding the Access-Control-Allow-Origin field in the response header on the server side and setting it to *, the resource can be accessed across domains from all domains.

Sample code:

// 在源B的服务器设置响应头
header('Access-Control-Allow-Origin: *');

3. Application of Ajax technology
Ajax (Asynchronous JavaScript and XML) is a technology that updates web page content by asynchronously loading data in the background. Through Ajax technology, websites can update data without refreshing the page, improving user experience.

Sample code:

// 源A的页面
<script>
var xhr = new XMLHttpRequest();
xhr.onreadystatechange = function() {
    if (xhr.readyState === 4 && xhr.status === 200) {
        // 处理返回的数据
        var data = JSON.parse(xhr.responseText);
        console.log(data);
    }
};
xhr.open('GET', 'http://b.com/data.php', true);
xhr.send();
</script>

// 源B的服务器
<?php
$data = array('name' => 'John', 'age' => 30);
echo json_encode($data);
?>

Through the above code, the page of source A uses Ajax technology to send an HTTP request to the server of source B and processes the returned data. As you can see, Ajax technology can be used to obtain the latest data without refreshing the page.

Summary: PHP's cross-domain requests and Ajax technology bring a richer interactive experience to the website. By using JSONP or setting response headers to solve cross-domain request problems, and using Ajax technology to load data asynchronously, websites can better meet user needs and improve user experience.

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