function checkform(e) {                        
    if ($('#review_makes').val() == '' || $('#review_models').val() == '') {
      alert('Please select car make and car model');
      return false;
    } else {
      return true;
    }
}

$(document).ready(function() {
      
      $('#review_makes option').removeAttr('selected');
      $('#review_makes option:first').attr('selected','selected');
      
      $('#review_makes').change(function(){
              var make = $('#review_makes').val();
              if (make == '') {
                      $("#review_models option[rel!='"+make+"']").remove();
                      $('#review_models').append('<option value="">Select a car model</option>');
              } else {
                      for (l=0;l<review_models.length; l++) {                                
                              var ddd=review_models[l].split(']['); 
                              for ( i=(ddd.length-1); i>=0; i-- ) {                        
                                      aaa=ddd[i].split('%*');
                                      if (aaa[1] == make)
                                      $('#review_models').prepend('<option value="'+aaa[0]+'" rel="'+aaa[1]+'">'+aaa[0]+'</option>');
                              }                                
                      }
                      $("#review_models option[rel!='"+make+"']").remove();
              }
      });                       
      
});