how to use ajax to send a javascript variable to PHP?

问题

I am using this javascript code to object a data of a td when pressing a button in an onclick event

  function rfk(element) {
    var element = element.parentElement.parentElement;

      var id = parseInt(element.children[0].innerText);

      $.ajax({
            url: './queryuser.php',
            type: "POST",
            dataType:'text',
            data: {'id': id},

        });
  }

when using an alert instead of var = id shows the value of the td

but this is failing the sentence of ajax when sending to php I do not know how to solve it

PHP code queryuser.php :

  <?php
    require("conextion.php");
    require("sql.php");

   $connect=start();

    $display= show($connect,$_POST['id']);

    disconnect=($connect);



   header("Location:index.php");
 ?>

Query sql:

    function show($con, $id){
    $query="    SELECT  user_name FROM  user 
    WHERE $id='?'";
    $call = $con->prepare($query);
    $call ->execute();

    return $call;
    }

回答1:

Pass the data like this to the ajax call (http://api.jquery.com/jQuery.ajax/): and select elements perfectly to get text

function rfk(element) {
  var element = element.parentElement.parentElement;
   var id = parseInt(element.children[0].innerText);
 $.ajax({
           url: '/queryuser.php',
            type: "POST",
            data: {id: id}    
        });
  }

来源：https://stackoverflow.com/questions/53489168/how-to-use-ajax-to-send-a-javascript-variable-to-php