PHP - Jquery Ajax .complete Forgets What Was Clicked

Hello, everyone. I have code that effectively calls a PHP page with AJAX  (no JQuery).  The PHP responds fine with an echo.  Here is the javaScript that calls the PHP so refreshing the page doesn't need to be done.

function deleteCategory()
{
	var e= document.getElementById("dropDown1");
	var var1 = e.options[e.selectedIndex].text;
	var xmlhttp = new XMLHttpRequest();
	xmlhttp.onreadystatechange = alerta() {
	if (this.readyState == 4 && this.status == 200) {
		
			document.getElementById("insert").innerHTML = xmlhttp.responseText;
		}
	};
	
	xmlhttp.open("GET", "deleteRow.php?q=" + var1 , true);
	xmlhttp.send();
 }

How do I call a PHP function on the same page while preserving the above AJAX.

Sincerely,

Joshua

Hello all

I have a php and jquery/ajax call I am using to create a file/send an email. I get all the contents from my textboxes but I want a message to display on the screen afterwards being success or fail. In my .ajax call My call is exiting right before the ‘success:’  part. Why is my call not succeeding? Any tips/help will be appreciated

Thank you

Html page just a form with a submit button
$(document).ready(function () {
    var form = $("#formData");
    
    $(form).on("submit", function (event) {
        event.preventDefault();
        $.ajax({
            type: "post",
            url: "file.php",
            data: $(this).serialize(),
            beforeSend: function () {
                $("#status").html('<span style="color:red;">Loading everything actually creating a .TXT file of contents...</span>')  //--works
            },
            success: function (data) { 
                var responseMsgType = "alert-" + data.type;
                var responseMsgText = data.message;
                // message below
                var alertBox = '<div class="alert ' + responseMsgType + ' alert-dismissable"><button type="button" class="close" ' +
                    'data-dismiss="alert" aria-hidden="true">&times;</button>' + responseMsgText + '</div>';
                if (responseMsgType && responseMsgText) {
                    $(form).find(".successArea").html(alertBox);
                    $(form)[0].reset();
                }
            }
        });
        return false;
    });
<?php
$controls = array('txtName' => 'Name', 'txtEmail' => 'Email', 'txtSubject' => 'Subject', 'txtMessage' => 'Message');
try {
	if(count($_POST)==0) { throw new \Exception ('Contact Form Message is empty'); }

	$headers = array('Content-Type: text/plain; charset="UTF-8";',
					 'From: ' . $email,
					 'Reply-To: ' . $email,
					 'Return-Path: ' .$email);

	$emailMessage = "You have a new message from your contact form" . PHP_EOL;
	$emailMessage .= "-------------------------------------------------------" . PHP_EOL;

	foreach($_POST as $key => $value){
        if(isset($controls[$key])) {
            $emailMessage .= "$controls[$key]: $value". PHP_EOL;
        }
    }
$mailMsg = "email6.txt";
	if(file_exists($filename) == false) {
		$fh = fopen($mailMsg, "w");
		fwrite($fh, $headers);
		fwrite($fh, $emailMessage);
		fclose($fh);
	} else {
		$fhexists = fopen($filename, "a");
		fwrite($fhexists, $content);
		fclose($fhexists);
	}

	$responseMessage = array("type" => "success", "message" => $successMessage);
}
catch (\Exception $ex) {
	$responseMessage = array("type" => "errorM", "message" => $errorMessage);
}
if(!empty($_SERVER['HTTP_X_REQUESTED_WITH']) && strtolower($_SERVER['HTTP_X_REQUESTED_WITH']) == 'xmlhttprequest') {
	$encodedJSON = json_encode($responseMessage);
	header("Content-Type: application/json");
	echo $encodedJSON;
} else {
	echo $responseMessage["message"];
}

I have a form with dropdown list that is populated with values from Sql Server table. Now i would like to use this selected item in SQL query. The results of this query should be shown in label or text field. So when a user selects item from dropdown menu, results from SQL query are shown at the same time.

I have two dropdown list at the moment in my form. First one gets all values from a column in table in SQL Server. And the second one should get a value from the same table based on a selection in first dropdown list.

When i load ajax.php i get 2 error mesages: 
Notice: Undefined index: machinery in C:\wamp64\www\gecko\ajaxfile.php on line  *8*
Warning: sqlsrv_fetch_array() expects parameter 1 to be resource, boolean given in C:\wamp64\www\site\ajaxfile.php on line  *16*

This is my code so far. I have tried to do it with this Ajax script. But i can only get first dropdown to work. The second dropdown(sub_machinery) does not show values, when first dropdown item is selected. The second dropdown should show values from databse table with this query( *$machineryID*  is first dropdown selected item): SELECT MachineID FROM T013 WHERE Machinery=".$machineryID.

Index.php

    <!doctype html>
      <?PHP
    $server = "server";
    $options = array(  "UID" => "user",  "PWD" => "pass",  "Database" => 
    "database");
    $conn2 = sqlsrv_connect($server, $options);
    if ($conn2 === false) die("<pre>".print_r(sqlsrv_errors(), true));
    echo " ";
    ?>
    <html>
    <head>
    <meta charset="utf-8">
    <title>Untitled Document</title>
    </head>
    
    <body>
                <section id="formaT2" class="formaT2 formContent">
                <div class="row">
                    <div class="col-md-2 col-3 row-color remove-mob"></div>
                    <div class="col-md-5 col-9 bg-img" style="padding-left: 0; 
    padding-right: 0;">
                        <h1>Form</h1>
                        <div class="rest-text">
                           <div class="contactFrm">
                              <p class="statusMsg <?php echo 
    !empty($msgClass)?$msgClass:''; ?>"><?php echo $statusMsg; ?></p>
                               
                                <form action="connection.php" method="post">
                                    <div>machinery</div>     
    <select id="machinery">
       <option value="0">--Please Select Machinery--</option>
       <?php 
       // Fetch Department
       $sql = "SELECT Machinery FROM T013";
       $machanery_data = sqlsrv_query($conn2,$sql);
       while($row = sqlsrv_fetch_array($machanery_data) ){
          $id = $row['Id'];
          $machinery = $row['Machinery'];
          
          // Option
          echo "<option value='".$id."' >".$machinery."</option>";
       }
       ?>
    </select>
    <div class="clear"></div>
                                    <div>Sub Machinery</div>
    <select id="sub_machinery">
       <option value="0">- Select -</option>
    </select>
                                    
                                    <input type="submit" name="submit" 
    id="submit" class="strelka-send" value="Insert">
                                    <div class="clear"> </div>
                                </form>
                             </div> 
                         </div>
                    </div>
                </div> 
            </section>
             </script>
          <script type="text/javascript">
          $(document).ready(function(){

        $("#machinery").change(function(){
            var machinery_id = $(this).val();
    
            $.ajax({
                url:'ajaxfile.php',
                type: 'post',
                data: {machinery:machinery_id},
                dataType: 'json',
                success:function(response){
    
                    var len = response.length;
     
                    $("#sub_machinery").empty();
                    for( var i = 0; i<len; i++){
                        var machinery_id = response[i]['machinery_id'];
                        var machinery = response[i]['machinery'];
                        
                        $("#sub_machinery").append("<option 
    value='"+machinery_id+"'>"+machinery+"</option>");
    
                    }
                }
            });
        });
    
    });
          </script>
    </body>
    </html>

Ajaxfile.php

<?php
    $server = "server";
    $options = array(  "UID" => "user",  "PWD" => "pass",  
    "Database" => "database");
    $conn2 = sqlsrv_connect($server, $options);
    if ($conn2 === false) die("<pre>".print_r(sqlsrv_errors(), true));
    echo " ";

    $machineryID = $_POST['machinery'];   // department id

    $sql = "SELECT MachineID FROM T013 WHERE Machinery=".$machineryID;
    
    $result = sqlsrv_query($conn2,$sql);
    
    $machinery_arr = array();
    
    while( $row = sqlsrv_fetch_array($result) ){
        $machinery_id = $row['ID'];
        $machinery = $row['MachineID'];
    
        $machinery_arr[] = array("ID" => $machinery_id, "MachineID" => 
    $machinery);
    }
    
    // encoding array to json format
    echo json_encode($machinery_arr);
    ?>

<!DOCTYPE HTML>
<html lang="en"> 
	<head>
		<meta charset="UTF-8">
		<title>Home Page</title>
	</head>
	<body>
	
	<div class="record" >
		<a href="record.php?id=<?php echo $record_id ?>"><?php echo $record_name; ?></a>
		<div class="delete-record">
			<a href="delete.php">Delete Record</a>
		</div>
	</div>	
	
	</body>
</html>
	

Browser HTTP client makes a request to a HTTP web server which makes a HTTP cURL request to a HTTP REST API which initiates a ReactPHP socket client to make a request to a socket server, and the socket server script eventually execute the following method:

    public function executeSpecificRequestCommand(array $data):bool {
        $status = $this->doSomething($data);
        return $status; //{success: $status} will be returned to the socket client
    }

All is good until doSomething()  takes a lot of time and results in a cURL error between the HTTP web server and HTTP REST API.  For this particular case, the task isn't meant to provide immediate feedback to the user, but to do some work and update the database, and as such, my desire is to return true status and then perform the work instead of extending the cURL timeout.

One option is to ran some process in the background and return status, but I don't think doing so is really right.  Using a queue seems excessive as I am already decoupled via the socket.  As such, I will probably just add some logic between the initial $string->on('data') and this executeSpecificRequestCommand() method to determine whether the success message should be returned before or after the method is complete.

Before doing so, however, I would like to know if there is a more appropriate approach to this scenario.  It appears that maybe a child process or a deferred might be appropriate, but am not sure whether I am going down the wrong path.

Background:
I'm comparing 2 styles of Ajax:
1.) "jquery style"
2.) "ActiveXObject Microsoft.XMLHTTP style"

Question:
Is one better (faster, more cross-browser compliant) than the other?

My experience:
Both seem equally fast. The Microsoft style is a bit longer, but I don't have to load jquery.js to my page!

Code Examples:

Jquery style on my PHP page:

function getInfo(ProductNumber){
$.ajax({
url:'Ajax-PHP-Page.php?ProductNumber='+ProductNumber,
success: function(html) {
document.getElementById("my_div").value = '';
document.getElementById("my_div").value = html;
}
});
}

Microsoft style on my PHP page:

function getInfo(ProductNumber) {
        if (window.XMLHttpRequest) {
            // code for IE7+, Firefox, Chrome, Opera, Safari
            xmlhttp = new XMLHttpRequest();
        } else {
            // code for IE6, IE5
            xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
        }
        xmlhttp.onreadystatechange = function() {
            if (this.readyState == 4 && this.status == 200) {
                document.getElementById("my_div").value = this.responseText;
            }
        };
    xmlhttp.open("GET","Ajax-PHP-Page.php?ProductNumber="+ProductNumber,true);
  xmlhttp.send();
}

Thank you!!