Ajax submit to self PHP file, but seems the PHP function do not execute

Question

Ajax submit to self PHP file, but seems the PHP function do not execute.

<?php

function request(){
    echo "<h1>requested</h1>";
}

?>
<html id="html">
<button id="btn_click" onclick="request1()">click</button>


</html>
<script  type="text/javascript">
    function request1(){
        document.write("<h1>been clicked</h1>");
        var xmlhttp = new XMLHttpRequest();

        xmlhttp.open("GET", "/index.php", true);
        xmlhttp.send();
    }
</script>

The JavaScript execute success, but seems the PHP code did not execute.

The PHP function `request` is never called. (That also assume the JS sends correctly, I use jquery for ajax interactions) — user3783243, Dec 01 '18 at 02:15
Working example please check the PHP fiddle http://phpfiddle.org/main/code/xfc2-wg1c — Raja Rama Mohan Thavalam, Dec 01 '18 at 02:34
@RajaRamaMohanThavalam Should probably only call `request()` if the request is an ajax request. Also doesn't appear to do anything with the ajax response, or i cant read vanilla js — user3783243, Dec 01 '18 at 02:36

score 2 · Accepted Answer · answered Dec 01 '18 at 02:42

To add to what gibberish said, however, there's more to it. You must also keep in mind you don't seem to be executing the function at all.

A PHP function does nothing unless it is called.

function request() {
  echo "<h1>Hello</h1>"
}

The function above will not be affected unless you call it:

request() // <h1>Hello</h1>

Also AJAX is best used when keeping requests simple. You send a request /path/to/file.php then that requests should return a plain text response or a JSON object, or a fully rendered static page if you are using a modal or some static item on your site.

/path/to/file.php

<?php

if( $_GET['clicked'] ) {

  // do whatever 

  echo json_encode([
    'user_id' => 1,
    'total_clicks' => $_GET['clicked'],
    'random_number' => rand(100, 999)
  ]);

}

The JS can easily handle the response:

function request(id) {
  return fetch(`/path/to/file.php?clicked=${id}`)
          .then(res => {
            console.log(res);
            body.innerHTML += res.user_id;
            body.innerHTML += res.total_clicks;
          })
          .catch(err => console.error(err));
}

This will be the simplest way to have your server return information from the DB and make your page content as interactive as you need it to be,.

Vinesh Goyal · Answer 2 · 2018-12-01T07:31:18.160

$_SERVER['HTTP_X_REQUESTED_WITH'] help us to detect an AJAX request

    <?php
//Check Here Ajax Request
if(isset($_SERVER['HTTP_X_REQUESTED_WITH']) && !empty($_SERVER['HTTP_X_REQUESTED_WITH']) && strtolower($_SERVER['HTTP_X_REQUESTED_WITH']) == 'xmlhttprequest'){
    function request(){
       echo "<h1>requested</h1>";
    }
    request();
    die;
}
?>
<html id="html">
    <body>
        <button id="btn_click" onclick="request1()">click</button>
        <div class="response" id="result" ></div>

        <script  type="text/javascript">
            function request1(){
                var xmlhttp = new XMLHttpRequest();
                xmlhttp.onreadystatechange = function() {
                if (xmlhttp.readyState == XMLHttpRequest.DONE) {   // XMLHttpRequest.DONE == 4
                       if (xmlhttp.status == 200) {
                           document.getElementById("result").innerHTML = xmlhttp.responseText;
                       }
                    }
                };
                xmlhttp.open("GET", "./index.php", true);
                xmlhttp.setRequestHeader('X-Requested-With', 'XMLHttpRequest'); // <-- ADD this
                xmlhttp.send();
            }
        </script>
    </body>
</html>

Ajax submit to self PHP file, but seems the PHP function do not execute

2 Answers2