从输入中检索值并将其发布在同一PHP中

Question

I want to read the value that is in the input box and based on that, create (with PHP in the same file) some dropdown boxes. After trying several hours I can't find a way to do this.

The HTML Input Field

<input type="text" onblur="sendData(this.value)" name="ingr_count" id="ingr_count" pattern="\d*" />

I have this JS/AJAX to read the value and post it in the PHP

function sendData(obj) {
            var xmlhttp;

            if (window.XMLHttpRequest) {
                xmlhttp=new XMLHttpRequest();
            } else {
                xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
            }

            xmlhttp.onreadystatechange=function() {
                if (xmlhttp.readyState==4 && xmlhttp.status==200) {
                    alert(obj);
                    // Do stuff when script returns
                }
            }

            xmlhttp.open("POST","script.php?count=" + obj.value + "&t="+Math.random(),true);
            xmlhttp.send();
        }

I also have this PHP to read the value

$src1= $_POST['count'];  
echo $src1; 

Commenting out everything bellow var xmlhttp; and alerting the obj will alert the obj but if I uncomment it won't even alert the value! :O .

Answer 1

After the comments of @Mura and @Fred-ii- I managed to complete my AJAX code. The problem was that when I recieved the value I couldn't use it in PHP. So when I read the value on AJAX I created a cookie and stored the input box value inside and after that I refresh the content of the PHP. So the final code is something like the below.

The HTML

<input type="text" onblur="sendData(this.value)" name="ingr_count" id="ingr_count" pattern="\d*" />

The JS/AJAX

function sendData(obj) {
            var xmlhttp;

             alert (obj);
            if (window.XMLHttpRequest) {
                xmlhttp=new XMLHttpRequest();
            } else {
                xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
            }

            xmlhttp.onreadystatechange=function() {
                if (xmlhttp.readyState==4 && xmlhttp.status==200) {
                    alert(obj);
                    // Do stuff when script returns
                }
            }


            document.cookie="count="+ obj;
            alert (obj);
            var x = document.cookie;
            alert (x);
            $("#main").load("script.php");

        }

The PHP

if (isset($_COOKIE["count"])){

 $src1= $_COOKIE["count"];

   echo $src1;

 setcookie('count', '', time()-300); 
} else { do whatever you want   }