title: jquery ajax response from variable from a target file
body: <p>I am sending username and password to some target file (auth.php) using jquery ajax.
  In auth.php file, i have many variables "var a1", "var b1".</p>
  
  <p>If  authentication success, the variable "a1" set to pass(a1='pass').</p>
  
  <p>My problem is how to access the only the "a1" variable from "auth.php" using the ajax response.</p>
  
  <p>small code is below:</p>
  
  <pre><code>$.ajax({
            url: "auth.php", 
            type: "POST",
            data: "dataString",
            success: function (txtBack) { 
  
             -- here i need to check the variable "a1" from auth.php
            }
  </code></pre>
  
  <p>Thanks in advance.</p>