使用js文件中的phpfile输出作为变量

Recently I am learning single page application, but I got a problem, the project I am working on is inside a folder that contain many folders, php js are folders in side the main folder, and each contain its type of files, the problem is that one of the php file called getmax.php gives me the maximum id ,I want to use this max(id) in a js file called module.js in order to give the new module the next id , the module.js should gives this id to another php file called insert.php ,the connection between the module.js and insert.php is working properly if I set the id manually . but I could not figure out how can I make it use the max(id) from the getmax.php file.

note: I noticed lately I'm using MySQL and I should used mysqli I will fix it later.

the getmax.php is:

<?php
// alle relevanten Tabellen abfragen und als json zurückgeben.


$json["status"] = "running";
$details[] = "started get_tables ";
// Include confi.php
include_once('confi.php');
//var_dump($_POST);
$request_body = file_get_contents('php://input');
// first store the given set of data to keep it for future analysis
$statement = "INSERT INTO tbl_archive (content) VALUES ('$request_body' );";
mysql_query($statement);
$input = json_decode($request_body, true);
// now check if valid user
$user = $input["user"];

$username = $user["username"];
$password = $user["password"];

if($password and $username){


    $mySQLstring = "SELECT username, password, id, create_user FROM tbl_user where username = '$username' ;";
    $json["statement"][] = $mySQLstring;
    $qur = mysql_query($mySQLstring);
    //var_dump ( $qur );
    if ($qur){
        $max = mysql_fetch_assoc($qur);
    }
    if ($max){
        $json["max"] = $max;
        if ($max["password"] == $password){
            $json["username"] = $username;
            $json["id"] = $max["id"];
            $json["create_user"] = $max["create_user"];
            $json["status"] = "ok";
            $tables = array("class", "class_user", "module", "module_class", "module_user", "rating", "student", "student_class");
            //$tables = array("class");
            foreach($tables as $table){
                if ( $table == 'module' ){
                $statement ='SELECT create_user, MAX(id) FROM tbl_'.$table;                 

                //$statement .= ' GROUP BY create_user' ;
                $statement .= ' WHERE create_user = 19 ' ;

                $qur = mysql_query($statement);
                if ($qur){
                    while($r = mysql_fetch_array($qur, MYSQL_ASSOC)){
                        //var_dump($r);
                        //echo (json_encode($r));
                        $result[$table][] = $r;
                    }
                }
                }
            }
            $json = array("status" => "ok", "data" => $result);
        }
    }
}



@mysql_close($conn);

/* Output header */
header('Content-type: application/json');
echo json_encode($json);
?>

PHP and JS are run on the server and client respectively, and as such you cannot call methods/functions of one from the other. AJAX exists to pass values between JS and serverside code.