JS 文本框輸入字數 顯示剩餘

     

//JS寫法

<script language="javascript">
        function keypress(text, label) {
            var count = document.getElementById(text).value.length;
            if (500 - count >= 0) {
                document.getElementById(label).innerHTML = "共可輸入500字，尚可輸入" + (500 - count) + "字";
            }
            else {
                document.getElementById(text).value = document.getElementById(text).value.substr(0, 500);
            }
        }
</script>

 

//控件名

<asp:Label ID="FBBAA043E" Text="共可輸入500字，尚可輸入500字" Width="370px" runat="server"></asp:Label><br />
                  <asp:TextBox  ID="FBBAA043" runat="server" Width="570px"  TextMode="MultiLine"
                        ontextchanged="FBBAA043_TextChanged" onkeyup="keypress('FBBAA043','FBBAA043E')" />