Parent Page: showModelessDialog ( "myDialog.htm", window, "status: false; dialogWidth: 300px; dialogHeight: 300px"); showModelessDiablog content page var pWin = dialogArguments; reference pWin .jsfunction () pWin .document.getElementById ("") Note Here, if you use Document, JSFunction () will not be called, and PWIN will inherit the Document of the original window. At this point, you should use PWIN.GETELEMENTBYID ('Identity'). Value = " NewVal "another parameter callback A.htm ===================