<script type="text/javascript">
    $(document).ready(function () {
        alert('function fired');
    $('.select').mouseleave( function () {
            alert('will hide');
            $('.select').hide();
        });
    });
  </script>

<div id="btndiv" style="height:373px;width:800px; border:10px  solid orange ">
    <div id="btndiv1" style="height:360px;width:800px; border: 1px solid orange  ;">
        <textarea  rows="10"  class="select"  id="editor1"> </textarea>
    </div>
</div>

$(this).attr('class');

var outside = $('#btndiv1 .select').attr('class') ;

    $('.select').mouseleave( function () {
           alert('will hide');
           $('.select').hide();
           var inside = $(this).attr('class') ;
     });

$("div textarea").attr("class")

$("div div textarea").attr("class")

$("#editor1").attr("class") //if u know id

$("div#btndiv textarea").attr("class")  // if u know id of div

$("div#btndiv").find("textarea").attr("class")

$('textarea','#btndiv1').attr('class');