使用JS

Question

我有3个文件，一个是HTML，PHP和JS。我有一个HTML按钮，我想通过Javascript触发单击PHP文件。我尝试了以下代码，但由于某种原因，每次都会给我错误消息：

JavaScript

function getOutput() {
    getRequest(
        'create_json.php', // URL for the PHP file
         drawOutput,  // handle successful request
         drawError    // handle error
    );
    return false;
  }  
  // handles drawing an error message
  function drawError() {
      var container = document.getElementById('output');
      container.innerHTML = 'Bummer: there was an error!';
  }
  // handles the response, adds the html
  function drawOutput(responseText) {
      var container = document.getElementById('output');
      container.innerHTML = responseText;
  }
  // helper function for cross-browser request object
  function getRequest(url, success, error) {
      var req = false;
      try{
          // most browsers
          req = new XMLHttpRequest();
      } catch (e){
          // IE
          try{
              req = new ActiveXObject("Msxml2.XMLHTTP");
          } catch(e) {
              // try an older version
              try{
                  req = new ActiveXObject("Microsoft.XMLHTTP");
              } catch(e) {
                  return false;
              }
          }
      }
      if (!req) return false;
      if (typeof success != 'function') success = function () {};
      if (typeof error!= 'function') error = function () {};
      req.onreadystatechange = function(){
          if(req.readyState == 4) {
              return req.status === 200 ? 
                  success(req.responseText) : error(req.status);
          }
      }
      req.open("GET", url, true);
      req.send(null);
      return req;
  }

<button id="submit" onclick="getOutput()">Submit</button>
<div id="output">waiting for action</div>

<?php
function get_data(){
$connect=mysqli_connect("localhost", "root", "root", "openingpage");
$query="SELECT * FROM created_list ";
$result=mysqli_query($connect, $query);
$list_data=array();
while($row=mysqli_fetch_array($result)){
  $list_data[]=array(
    'ModelID'   => $row["ModelID"],
    'ImageID'   => $row["ImageID"],
    'ListID'    => $row["ListID"]
   );
}
return json_encode($list_data);
}

$file_name=date('d-m-Y').'.json';
if(file_put_contents($file_name,get_data())){
echo $file_name.' file created';    
}
else{
echo 'There is some error';
}
?>

我总是收到“糟糕：出现错误！”信息。我为什么无法得到它。我检查了100次以上的代码，但找不到此代码出了什么问题。 预先感谢。