jquery - ajax receives response from php but can not use with ajax

Solution:

If the response from your PHP is:

<{"response" : "2"}
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This would be an incorrectly formatted JSON string. This would be created by the extra< you have at the beginning of the document. I would advise you have the following PHP Opener:

<?php
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This should correct the issue so the JSON Response would be:

{"response" : "2"}
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It will be properly parse at that point.

Example

<?php
$id = (int)$_POST['reccount'];
$link = mysqli_connect("localhost", "root", "", "testsite");
header('Content-Type: application/json');
if($link === false){
  die("{\"error\": \"Could not connect. " . mysqli_connect_error() . "\"}");
}
$sql = "SELECT * FROM paper WHERE ID=$id";
if(mysqli_query($link, $sql)){
  $result = mysqli_query($link, $sql);
  while($row = mysqli_fetch_array($result)) {
    $data['response']= $row['response'];
    $data['ansnum'] = $row['q_no'];
  }
  echo json_encode($data);
} else {
  echo "{\"error\": \"Unable to execute $sql. " . mysqli_error($link) . "\"}";
}
mysqli_close($link);
?>
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In my example, I cast the POST data to Integer to help ensure a malicious user does not get to send anything other than a digit. I also only send JSON data, even when sending an error. Using theheader() helps define the data for the browser.

$.ajax({
  type:"POST",
  url:"<?php echo base_url();?>/shortfiles/loadans.php",
  data: {reccount: reccount},
  dataType:"JSON",
  success: function(data){
    console.log(data);
    if(data.error !== undefined){
      alert(data.error);
    } else {
      $('#respond').text(data.response);
    }
  }
});
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Hope that helps.

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