刷新DIV标记的内容，其中包括PHP函数调用

At the heart of the problem I am attempting to use the value of a HTML dropdown menu to call a php function without reloading the entire page. Given that PHP is a server side language I have incorporated JQuery to handle the onChange event in the hope of only reloading a portion of the page. The PHP function that I want to call (i.e., wp_cart-button_for_product) prints out an add to cart button, but the variables associated with the add to cart button ultimately depend upon the drop down menu. The div tag that I want to reload (i.e., button-reload) is on the current page, but the URL changes depending upon the product. I have experimented with the load and html methods, but have had no luck.

<script type = "text/javascript">
  function productchange() 
  {
      var currentrow = $('#productcategory1').val();
      $("#jsvar").val(currentrow);
      $.ajax({
        type: "GET",
        url: "http://www.example.com/wp-content/themes/themeX/storevar.php",
        data: {'jsvar': currentrow},
        complete: function(){
              $('#button-reload').load("http://www.example.com/wp-content/themes/themeX/printbutton.php #button-reload > *");
      //      $('#button-reload').html($('#button-reload',data).html);
      //      $('#button-reload').load(location.href "#button-reload > *");
            }});      
      return false;
  }
  </script>

<div id = "button-reload">
      <?php echo print_wp_cart_button_for_product($products[$_SESSION['currentrow']]["Product"], $products[$_SESSION['currentrow']]["Price"]); ?>
  </div>

  <form method="get" action="http://www.example.com/wp-content/themes/themeX/storevar.php">
      <input type="hidden" name="jsvar" id="jsvar" value="" />
  </form>

Storevar.php

<?php
    session_start();
    $currentrow = $_GET['jsvar'];
    echo "Current Row = $currentrow";
    $_SESSION['currentrow'] = $currentrow;
    echo "Session Currentrow =".$_SESSION['currentrow'];
?>

Printbutton.php

<div id="button-reload">
    <?php echo print_wp_cart_button_for_product($products[$_SESSION['currentrow']]["Product"], $products[$_SESSION['currentrow']]["Price"]); ?>
</div>

After hours of experimentation:

 <script type = "text/javascript">
 function productchange() 
  {
      var currentrow = $('#productcategory1').val();
      alert(currentrow);
      $("#jsvar").val(currentrow);
      $.ajax({
         type: "GET",
         url: "http://example.com/wp-content/themes/themeX/storevar.php",
         data: {'jsvar': currentrow},
         success: function(response){
              alert(response);
              var pathname = window.location.href;
              alert(pathname);
              $('#button-reload').load(pathname + " #button-reload", function(responseTxt, statusTxt, xhr){
              if(statusTxt=="success")
                alert("Content loaded successfully!");
                if(statusTxt=="error")
                  alert("Error: "+xhr.status+": "+xhr.statusTxt);
                  });
  return false;
  }
  </script>

function productchange() 
{
var currentrow = $('#productcategory1').val();
$('#button-reload').load("http://www.example.com/wp-content/themes/themeX/printbutton.php", {jsvar: currentrow});
}

should be enough.

You were executing an ajax request and then calling load inside the success callback. Check the jquery documentation http://api.jquery.com/load/

EDIT You are missing "session_start();" in your printbutton.php. You can also add your storage code in there so you only need to make one ajax call.

Printbutton.php

<?php
    session_start();
    $currentrow = $_GET['jsvar'];
    echo "Current Row = $currentrow";
    $_SESSION['currentrow'] = $currentrow;
?>
<div id="button-reload">
    <?php echo print_wp_cart_button_for_product($products[$_SESSION['currentrow']]["Product"], $products[$_SESSION['currentrow']]["Price"]); ?>
</div>