textarea 입력자 수 제한

<script type="text/javascript">

        function limitChars(id, count) {

            var obj = document.getElementById(id);

            if (obj.value.length > count) {

                obj.value = obj.value.substr(0, count);

            }

        } 

    </script>

HTML 코드:

  <div>

         ：<br />

        <textarea name="contid" runat="server" rows="2" cols="20" id="txtProcIdea" onkeydown="limitChars('txtProcIdea', 10)" 

            onchange="limitChars('txtProcIdea',10)" style="height: 49px; width: 580px;"></textarea>

    </div>