Ajax响应重复循环两次以显示数据

Question

以下是我的ajax：它显示从php脚本数据库中提取的数据。我var_dump结果在PHP页面看到数组的大小。它说数组大小（11）。

但是当传递给ajax页面时，它将返回11个数据两次。我使用console.log（$ data.length）来查看返回的数据集的数量。它虽然显示了11次。在我的下面的代码是什么让循环显示两次请吗？

$("form").on("submit", function() { 
    var data = { 
     "action": "test" 
    }; 

    data = $(this).serialize() + "&" + $.param(data); 
    $.ajax({ 
     type: "POST", 
     dataType: "json", 
     url: "ajax2.php", 
     data: data, 

     success: function (data) { 

      getData=data; 
      $("#main_content").slideUp("normal",function(){ 
      $(".the-return").show(); 
      if(data!=""){ 
       console.log(data.length); 
      for (i = 0; i < data.length; i++) { 
$(".the-return").append("<div class='inside_return'><section class='row'><div class='small-12 medium-6 large-10 large-centered columns d_result'><div class='text-center post_id'>" + data[i].id +"</div><div class='small-12 medium-12 large-9 columns subject'>"+ data[i].subject+" Instructor</div><div class='small-12 meidum-12 large-3 columns rate'>" + data[i].rate +"</div><span class='hourly'>hourly</span><div class='small-12 medium-12 large-12 text-center name'>" + data[i].name +"</div><div class='small-12 medium-12 large-4 columns plusneg'><img src='img/happy.png'>" + data[i].plus+"<br/><img src='img/sad.png'>"+ data[i].neg+"</div><div class='small-12 medium-12 large-4 columns gender text-center'>Male<br/>Availabiliy:<br/>Mornings:" + data[i].weekM+"<br/>Afternoons:<br/>"+ data[i].endA+"Evening:"+ data[i].weekE+"</div><div class='small-12 medium-12 large-4 columns score text-center'><h6>Reputation score</h6>"+ data[i].reputation+"</div><div class='row'><div class='small-12 medium-12 large-5 columns shortlist text-center'>Add to Shorlist</div><div class='small-12 medium-12 large-5 columns gettutor text-center'>Get Tutor</div></div><div class='small-12 medium-12 large-12 columns text-center date'>Posted on:<span class='elec'>15 Apr 2015</span></div></div></section></div>"); 

      //alert(data[i].name) 
      } 
      }else{ 
       $(".the-return").hide(); 
       $(".the-return-fail").slideDown(1000); 
      } 

      });//closes #main_content 
     } 


    }); 
    return false; 


}); 

PHP脚本

<?php 
if (is_ajax()) { 
    if (isset($_POST["action"]) && !empty($_POST["action"])) { //Checks if action value exists 
    $action = $_POST["action"]; 
    switch($action) { //Switch case for value of action 
     case "test": test_function(); break; 
    } 
    } 
} 

//Function to check if the request is an AJAX request 
function is_ajax() { 
    return isset($_SERVER['HTTP_X_REQUESTED_WITH']) && strtolower($_SERVER['HTTP_X_REQUESTED_WITH']) == 'xmlhttprequest'; 
} 

function test_function(){ 
$return = $_POST; 
//$return='{"sub":{"1":"","2":""},"postcode":"56000","slider1":"100","action":"test"}'; 



$return["json"] = json_encode($return); 
// echo json_encode($return); 
$data = json_decode($return["json"], true); 
    //var_dump($data); 

include('inc/config.php'); 



$postcode=$data['postcode']; 


$rate=$data['slider1']; 

$key =array_keys($data['sub']); 
//print_r($key); 
$pricing2 = $data['slider1']; 
$pricing = $pricing2 * 1.90; 
$postcode = $data['postcode']; 


$bindings = array(); 
$bindings[] = array(":pricing", $pricing, PDO::PARAM_STR); 
$bindings[] = array(":postcode", $postcode, PDO::PARAM_STR); 

$key_placeholders = array(); 
foreach($key as $k => $v) { 
    $placeholder = ":subid".$k; 
    $bindings[] = array($placeholder, $v, PDO::PARAM_INT); 
    $key_placeholders[] = $placeholder; 
} 

$sql = "SELECT * FROM posts,subjects " 
     . "WHERE posts.subid IN (". implode(",",$key_placeholders).") " 
     . "AND posts.pricing <=:pricing " 
     . "AND posts.Poscode=:postcode " 
     . "AND posts.subid=subjects.subid " 
     . "ORDER BY posts.Poscode " 
     . "DESC LIMIT 60"; 

$statement = $pdo->prepare($sql); 
foreach($bindings as $b) { 
    $statement->bindValue($b[0],$b[1],$b[2]); 
} 
$statement->execute(); 
$json = array(); 
while($row = $statement->fetch()) { 
    array_push($json, array("name" => $row['Name'], "id" => $row['PostUUID'],"rate" => $row['pricing'],"postcode" => $row['Poscode'],"subject" => $row['subname'],"reputation" => $row['Reputation'],"plus" => $row['ReviewPlus'],"neg" => $row['ReviewNeg'],"weekM" => $row['week_morning'],"weekA" => $row['week_afternoon'],"weekE" => $row['week_evening'],"endM" => $row['weekend_morning'],"endA" => $row['weekend_afternoon'],"endE" => $row['weekend_evening'],"postDate" => $row['date'])); 
} 
header('Content-Type: application/json'); 
echo json_encode($json); 
//var_dump($json); 
} 

?> 

Answer 1

我加入这一行的形式提交，以避免重复提交后。

$('form').submit(function(){ 
    **$(this).find(':submit').attr('disabled','disabled');** 
});