$.ajax always go to error callback function

Question

I am trying to check if a file exist or not but when I run the code it always go to error callback function even if the filename is the url of an existing file. Why does $.ajax enter only the error callback function?

$.ajax({
       url: filename,
       type: 'GET',
       dataType: 'text',
       async: false,
       cache: false,
       success: function ()
       {
            alert('file is found.');
       },
       error: function ()
       {
            alert('file is not found.');
       }
 });

Is your file name is link(remote file)?If so file_exists function always return false.Type here your file name — Shaiful Islam, Nov 19 '14 at 15:11
Instead of type: 'GET', this SO answer suggests using 'HEAD' - there are other useful answers as well - possible duplicate: http://stackoverflow.com/questions/3646914/how-do-i-check-if-file-exists-in-jquery-or-javascript — ron tornambe, Nov 19 '14 at 15:22

score 0 · Answer 1 · answered Nov 19 '14 at 15:17

0

There could be more problems:

The file might not be where you think it is
The file might crash and fail to respond
The file might run for a long while and your request might crash due to timeout

You should check all these possibilities.

answered Nov 19 '14 at 15:17

Lajos Arpad

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score 0 · Answer 2 · answered Nov 19 '14 at 15:19

You have to do a script jquery with a file php.

$.ajax({ url: verify.php, 
        data: {file: filename}
        type: 'GET', dataType: 'text', async: false, cache: false, 
        success: function (data) { if(data){alert('file is found.');} }, 
        error: function () { alert('file is not found.'); } 
 });

And the code php

<?php
     echo file_exists($_GET['file']);
?>

Or you can check the permissions of the file

score 0 · Answer 3 · answered May 23 '15 at 02:02

I think your return string data is very long. so the JSON format has been corrupted. You should change the max size for JSON data in this way :

Open the Web.Config file and paste these lines into the configuration section.

<system.web.extensions>
  <scripting>
    <webServices>
      <jsonSerialization maxJsonLength="50000000"/>
    </webServices>
  </scripting>
</system.web.extensions>

$.ajax always go to error callback function

3 Answers3