How to call ajax function from GridView ButtonField in ASP.Net

<asp:GridView ID="GridView1" runat="server" BackColor="White" BorderColor="#3366CC" BorderStyle="None" BorderWidth="1px" CellPadding="4" Height="162px" OnSelectedIndexChanged="GridView1_SelectedIndexChanged" onrowediting="GridView1_RowEditing" Width="320px"> <Columns> <asp:ButtonField ButtonType="Button" CommandName="Edit" HeaderText="Edit" ShowHeader="True" Text="Edit" /> </Columns></asp:GridView>

i have code like this ...I need to call ajax fun which stops refreshing the page mwhen this button which is in grid is clicked . can any one help?