Javascript $.post函数（响应）未成功返回

我使用select2在一个输入元素中获取多个成员名称。下面是我的ajax代码：（在我的form.php中）

我的服务器端有这样的代码：（我只写这个想法，因为它太长了）

validation.php

 <?php
    $day =  mysqli_real_escape_string($conn, $_POST['day']);
    $venue = mysqli_real_escape_string($conn, $_POST['venue']);
    $time = mysqli_real_escape_string($conn, $_POST['time']);

    if(!isset($_POST['member_name'])) {
       echo "enter member names";
    } else {
        foreach($_POST['member_name'] as $selectedOptions) {

          *query data from database to check if one of the members selected 
           already exists in my group.
          *query data form database to check if one of the members selected is 
           my leader.
          *query data from database to check if one of the members selected 
           already belongs to someone else's group.

          if (already exists in my group) {
             echo "Cannot add. Already in your group";
          } elseif (is my leader) {
             echo "Cannot add leader";
          } elseif (belongs to someone else) {
             echo "Cannot add from someone else's group";
          } elseif (empty($day)) {
             echo "Enter day";
          } elseif (empty($venue)) {
             echo "Enter venue";
          } elseif (empty($time)) {
             echo "Enter time";
          } else {
             *insert data to the database
             echo "success";
          }
        }
    }

?>

---

请尝试以这种方式从循环外部返回输出

$output = "";
foreach($_POST['member_name'] as $selectedOptions) {

      *query data from database to check if one of the members selected 
       already exists in my group.
      *query data form database to check if one of the members selected is 
       my leader.
      *query data from database to check if one of the members selected 
       already belongs to someone else's group.

      if (already exists in my group) {
         $output = "Cannot add. Already in your group";
      } elseif (is my leader) {
         $output ="Cannot add leader";
      } elseif (belongs to someone else) {
         $output ="Cannot add from someone else's group";
      } elseif (empty($day)) {
         $output ="Enter day";
      } elseif (empty($venue)) {
         $output ="Enter venue";
      } elseif (empty($time)) {
         $output ="Enter time";
      } else {
         *insert data to the database
         $output ="success";
      }
    }

    echo $output;
    exit;

添加
console.log（结果）在js中的
函数（结果）{
之后查看服务器响应我已经看到php在前后添加空格。尝试修剪响应字符串。正如Rulisp console.log所述，调试.console.log（“AA”+结果+“AA”）的第一步是调试.console.log在前后添加内容，以便知道是否有空格。感谢您的建议。现在，我已将console.log（result）放在函数（result）之后，但它不会在控制台中打印任何内容。但实际发生的情况是，我忘了提到，一旦它通过所有验证约束，数据实际上会被插入数据库，但不会重新加载页面。因此，会调用错误消息“无法添加。已在您的组中”。您是一个救生员！谢谢老兄！我不知道为什么我没有想到。我之前一直忙于处理这件事，我忘了调试尽可能简单的东西。再次感谢！@Eric，欢迎你。我真的很高兴知道你的问题已经解决了。
$output = "";
foreach($_POST['member_name'] as $selectedOptions) {

      *query data from database to check if one of the members selected 
       already exists in my group.
      *query data form database to check if one of the members selected is 
       my leader.
      *query data from database to check if one of the members selected 
       already belongs to someone else's group.

      if (already exists in my group) {
         $output = "Cannot add. Already in your group";
      } elseif (is my leader) {
         $output ="Cannot add leader";
      } elseif (belongs to someone else) {
         $output ="Cannot add from someone else's group";
      } elseif (empty($day)) {
         $output ="Enter day";
      } elseif (empty($venue)) {
         $output ="Enter venue";
      } elseif (empty($time)) {
         $output ="Enter time";
      } else {
         *insert data to the database
         $output ="success";
      }
    }

    echo $output;
    exit;