How to jump to the upper page or return to the previous page in php

In web applications, page jump is a common operation that takes users to other pages to enable users to complete more operations. In PHP, page jumps can be achieved using the header() function. However, sometimes we need to jump to the upper page or return to the previous page. Below, I will introduce how to use PHP to achieve this jump.

To understand how to jump to the upper page or return to the previous page, you first need to understand how PHP handles HTTP requests. In most cases, when a user enters a URL in the browser, the browser initiates an HTTP request to the server. On the server side, PHP will parse these requests, process them according to different conditions, and finally return the results to the browser. So when we perform a page jump in PHP, we are actually telling the browser to send an HTTP request to another URL.

Jump to the upper level page

Jump to the upper level page means to jump to the upper level page of the current page, which may be where the user links to the current page. page, or may be the parent page of the current page. In PHP, you can use the $_SERVER['HTTP_REFERER'] variable to get the URL of the previous page. This variable stores the URL from which page the user linked to.

The following is the code for how to use the header() function to jump the user to the previous page:

<?php // 获取上一级页面的URL
$redirectURL = $_SERVER[&#39;HTTP_REFERER&#39;];
// 跳转到上一级页面
header(&#39;Location: &#39; . $redirectURL);
exit;
?>

In the above code, we first obtain the page from which the user is linked. URL, and then pass it to the header() function as the value of the Location header information. Finally, we use the exit statement to terminate the execution of the current PHP script. This tip is important because in the HTTP protocol, the Location header information will tell the browser to send a request to the specified URL, and the PHP script will continue to run. If there is no exit statement, the PHP script will continue to execute downwards and eventually the page will jump. The transfer won't happen.

Back to the previous page

Back to the previous page means taking the user back to the page they just visited. In PHP, you can use the $_SERVER['HTTP_REFERER'] variable to get the URL of the page the user visited before, and then use the history.back() method in JavaScript to implement the return operation.

The following is the code to return to the previous page:

<?php // 获取用户之前访问的页面的URL
$backURL = $_SERVER[&#39;HTTP_REFERER&#39;];
// 使用JavaScript实现退回操作
echo &#39;<script>history.back();';
?>

In the above code, we first obtain the URL of the page the user visited before, and then output a line of JavaScript in PHP Code, when this code is executed on the browser side, the history.back() method will be called to take the user back to the page they just visited.

Conclusion

By using the header() function and JavaScript, we can easily implement the function of jumping to the upper page or returning to the previous page in PHP. This functionality can make web applications more user-friendly and easier to use. It is worth noting that when executing page jumps, we need to pay attention to the use of exit statements and Location header information to ensure that the jump behavior occurs.

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