文本框同步输入

  <asp:TextBox ID="txtItemText" runat="server" CssClass="index_input" Width="259px" onkeyup="syncValue();"/>

function syncValue()
        {
            var txtItemText = document.getElementById('<%=Me.txtItemText.ClientID %>');
            var txtItemValue = document.getElementById('<%=Me.txtItemValue.ClientID %>');
           
            txtItemValue.value = txtItemText.value;
        }