Communicating from child window to parent window

Question

I'm been trying to communicate a child page with a parent page using window.opener, but I can't make it work. This is an example of what I've been working on (from child to parent). Any idea?
<$-HTML>
<$-HEAD>
<$-TITLE>
Ventana hija
<$-/TITLE>
<$-SCRIPT Language="javascript">
function cerrar() {
     alert(window.opener.document.url())
     window.opener.frmPadre.field1.Value = document.frmHijo.field1.value;
     window.opener.frmPadre.field2.Value = document.frmHijo.field2.value;
     window.opener.frmPadre.field3.Value = document.frmHijo.field3.value;
     document.frmHijo.valor.value = document.frmHijo.field1.value;
     window.opener.frmPadre.btnSubmit.focus();
<$-/script>
<$-/HEAD>
<$-BODY>
<$-form name = frmHijo>
<$-input type = text name = field1><$-br>
<$-input type = text name = field2><$-br>
<$-input type = text name = field3>
<$-input type = button name = btnSubmit Value = "DEVOLVER" onClick = cerrar()>
<$-/form>
<$-/BODY><$-/HTML>
The parent window hast a form name frmPadre with those 3 fields.

Answer 1

Javascript is not java, but here are a couple of tips for debugging:
You can use the browser address bar to alert stuff
ie : put this into the address bar of your browser and see what happens: javascript:alert("Hello world")
I would recommend you progress like this - slowly building up the link until you find where you go wrong.
In this case, I think you missed out a "document"
javascript:alert(window.opener)
javascript:alert(window.opener.frmPadre)
javascript:alert(window.opener.document.frmPadre)
javascript:alert(window.opener.frmPadre.field1)
Also just as a tip, cross browser scripting is a lot easier to maintain if you limit your self to calling FUNCTIONS in other windows.
ie rather than setting the values in the other windows textfields, call a function (with parameters) which does it.
eg in this case it might be:
window.opener.setPadreFields(document.frmHijo.field1.value, document.frmHijo.field2.value, document.frmHijo.field3.value)
The function would take the parameters and put them in the appropriate place on the form.
Doing it this way decouples the pages a little - you only interact with the other page via the function (single point of entry) and if you modify the page in the future (eg change the name of a field) it is much easier to find everywhere you need to do this.
Hope this helps,
evnafets