title: What does $.active means in following jQuery code?
body: <p>I'm using following jQuery libraries in my project. Following is the code for adding them:</p>
  
  <pre><code>&lt;script src="jquery-1.9.1.min.js"&gt;&lt;/script&gt;
      &lt;script src="jquery-ui-1.10.0.custom.min.js"&gt;&lt;/script&gt;
  </code></pre>
  
  <p>Now the function which is written by previous developer as follows:</p>
  
  <pre><code>function add_rebate_by_product() {
    if($.active &gt; 0) { //or $.active  //What this $.active does   
      request_inprogress();
    } else {
      var manufacturer_id = $("#company_id").val();
      var rebate_no       = $('.well').length;
      var site_url        = $('#site_url').val();
  
      if ($('.well').length&gt;=0) { 
        rebate_no = rebate_no+1;
      }
        $('.add_new_rebate').attr('disabled','disabled');
      }
  
      $.ajax({
        type: "POST",
        url: "add_rebate_by_product.php",
        data: {'request_type':'ajax', 'op':'create_rebate', 'rebate_no':rebate_no, 'manufacturer_id':manufacturer_id},  
        beforeSend: function() { 
          $('.load_img').html("&lt;img src='"+site_url+"img/ajax-loader.gif' class='load' alt='Loading...'&gt;");
        },
        success: function(data) {
          if(jQuery.trim(data)=="session_time_out") {
            window.location.href = site_url+'admin/login.php?timeout=1';              
          } else {
            $('.rbt').append(data);
            $('.add_new_rebate').removeAttr('disabled');
  
            //code for state select control to make functionality workable in newly added rebate block
            $('.states').multiselect({
              includeSelectAllOption: true,
              maxHeight: 150
            });
            //code for datepicker control to make functionality workable in newly added rebate block
            $(".date_control").datepicker({
              dateFormat: "yy-mm-dd"
            });                   
          }
          $('.load').remove();
        }
      });
  //}
  }
  </code></pre>
  
  <p>Now can someone please explain what the following files does and what's it's importance?</p>
  
  <pre><code>if($.active &gt; 0) { //or $.active        
          request_inprogress();
        }
  </code></pre>
  
  <p>Thanks in advance.</p>