[Javascript] Page A <script type = "text/javascript"> function popUp (url) {objSubWin = window. open (url, "Popup", "toolbar = no, scrollbars = no, location = no, statusbar = no, menubar = no, resizable = 0, width = 300, height = 80 "); objSubWin. focus ();} function SetValue (val) {var amount = document. getElementById ('<% = TextBoxAmount. clientID %> '); amount. value = val ;}</script> [csharp] <asp: TextBox ID = "TextBoxAmount" runat = "Server" Enabled = "false"> </asp: TextBox> <asp: button ID = "Button1" runat = "server" Text = "Call child window" OnClientClick = "popUp ('pageb. aspx ') "/> B page: <script type =" text/javascript "> function isNumeric (keyCode) {return (keyCode >=48 & keyCode <= 57) | keyCode = 8)} function calc () {if (window. opener! = Null &&! Window. opener. closed) {var qty = document. getElementById ('<% = TextBoxqty. clientID %> '); var price = document. getElementById ('<% = TextBoxPrice. clientID %> '); window. opener. setValue (parseInt (qty. value) * parseInt (price. value) }}</script> quantity <asp: TextBox ID = "TextBoxqty" runat = "server" onkeydown = "return isNumeric (event. keyCode); "onpaste =" return false; "Width =" 50 "> </asp: TextBox> * unit price <asp: textBox ID = "TextBoxPrice" runat = "server" onkeydown = "return isNumeric (event. keyCode); "onpaste =" return false; "Width =" 50 "> </asp: TextBox> <asp: button ID = "Button1" runat = "server" Text = "Calculate" OnClientClick = "calc ()"/>