How to use IS_AJAX in ThinkPHP to determine the problem of Ajax in native JS

The content of this article is about using IS_AJAX in ThinkPHP to determine the solution to Ajax problems in native JS. It has certain reference value. Friends in need can refer to it. Hope it helps.

Problem:

When using native js to initiate an Ajax request in ThinkPHP, the controller cannot use IS_AJAX for judgment. There is no problem using ajax in jQuery.

In ThinkPHP, there is a constant IS_AJAX that determines the ajax request;

Ajax requests are commonly used in two situations: one is the ajax request of native js, and the other is the ajax of jQuery ask.

Analysis:

First look at the header information when using ajax to send a request in jQuery:

Accept: application/json, text/javascript, */*; q=0.01
Accept-Encoding: gzip, deflate, br
Accept-Language: zh-CN,zh;q=0.9
Connection: keep-alive
Content-Length: 22
Content-Type: application/x-www-form-urlencoded; charset=UTF-8
Cookie: PHPSESSID=ns9mjve234erh0qerlcl180v52
Host: localhost
Origin: http://localhost
Referer: http://localhost/ok/
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/547.36 (KHTML, like Gecko) Chrome/71.0.3578.98 Safari/547.36
X-Requested-With: XMLHttpRequest

Then look at the use The header information when the native ajax in JS sends the request:

Accept: */*
Accept-Encoding: gzip, deflate, br
Accept-Language: zh-CN,zh;q=0.9
Connection: keep-alive
Cookie: PHPSESSID=ns9mjve234erh0qerlcl180v52
Host: localhost
Referer: http://localhost/tp/
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/547.36 (KHTML, like Gecko) Chrome/71.0.3578.98 Safari/547.36

Then check how the constant IS_AJAX is defined in TP:

In the tp3.2.3 version
\ ThinkPHP\Library\Think\App.class.php (Line:49)

define('IS_AJAX',       ((isset($_SERVER['HTTP_X_REQUESTED_WITH']) && strtolower($_SERVER['HTTP_X_REQUESTED_WITH']) == 'xmlhttprequest') || !empty($_POST[C('VAR_AJAX_SUBMIT')]) || !empty($_GET[C('VAR_AJAX_SUBMIT')])) ? true : false);

You will find the following:

Use jquery to send ajax When making a request, there is one more request header X-Requested-With: XMLHttpRequest than using ajax in native js.

And ThinkPHP uses the principle of judging whether there is a request header to define the constant IS_AJAX.

So how to solve this problem?

Set a corresponding request header information when sending an ajax request.

function page( page )
{
    var ajax = new XMLHttpRequest()
    ajax.open( 'get', '__URL__/show?page='+page, true )
    ajax.setRequestHeader("X-Requested-With", "XMLHttpRequest");
    ajax.send()
    ajax.onreadystatechange = function ()
    {
        if ( ajax.readyState == 4 && ajax.status == 200 ) 
        {
            document.getElementById( 'box' ).innerHTML = ajax.responseText;
        }
    }
}

After setting up, look at the request header information again. Compared with the previous one, there is one more

Accept: */*
Accept-Encoding: gzip, deflate, br
Accept-Language: zh-CN,zh;q=0.9
Connection: keep-alive
Cookie: PHPSESSID=ns9mjve234erh0qerlcl180v52
Host: localhost
Referer: http://localhost/tp/index.php/Home/Index/show
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/547.36 (KHTML, like Gecko) Chrome/71.0.3578.98 Safari/547.36
X-Requested-With: XMLHttpRequest

The problem is solved.

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