<script type="text/javascript"> function TXT_Value() { var value = document.getElementById('<%=TextBox1.ClientID%>').value; alert(value); return false; }</script>
<form id="form1" runat="server"> <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox> <asp:Button ID="Button1" runat="server" Text="Button" OnClientClick="return TXT_Value();" /> </form>
var value=$("#<%=TextBox1.ClientID%>").val();
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