I can display the value of the following input box with
alert(parent.My Frame.document. MyForm.MyInput. value);
But if the frame, the form or the input box doesn't exist I get of course an
error message.
How can I figure out before I display the value if the frame 'MyFrame', the
form 'MyForm' and also the input box 'MyInput' exists without getting an
error message?
Stefan
28  2102 
Stefan Mueller wrote: I can display the value of the following input box with
alert(parent.My Frame.document. MyForm.MyInput. value);
But if the frame, the form or the input box doesn't exist I get of course an
error message.
Use object/feature detection:
<http://jibbering.com/faq/#FAQ4_26>
That FAQ is mainly about checking certain features a browser implements
but those property or object checks can also be applied to your problem.
There is an example in there.
--
Martin Honnen http://JavaScript.FAQTs.com/
Stefan Mueller wrote: I can display the value of the following input box with
alert(parent.My Frame.document. MyForm.MyInput. value);
But if the frame, the form or the input box doesn't exist I get of course an
error message.
How can I figure out before I display the value if the frame 'MyFrame', the
form 'MyForm' and also the input box 'MyInput' exists without getting an
error message?
Perhaps something similar to this..
function myFoo()
{
for(;;) {
if(parent.MyFra me)if(parent.My Frame.document)
if(parent.MyFra me.document.get ElementById("My Input"))
break;
setTimeout("myF oo()",1000);ret urn;
}// End forever
alert(parent.My Frame.document. MyForm.MyInput. value);
}
--
--.
--=<> Dr. Clue (A.K.A. Ian A. Storms) <>=-- C++,HTML, CSS,Javascript
--=<> Internet Programming since 1994 <>=-- DHTML NSAPI TCP/IP
--=<> http://resume.drclue.net <>=-- AJAX, SOAP, XML, HTTP
--=<> http://www.drclue.net <>=-- SERVLETS,TCP/IP, SQL
--.
Dr Clue wrote: Perhaps something similar to this..
Certainly not!
function myFoo()
{
for(;;) {
if(parent.MyFra me)if(parent.My Frame.document)
if(parent.MyFra me.document.get ElementById("My Input"))
break;
I have seldom seen such a ridiculous piece of source code.
1. Tight loops are the way to the Dark Side.[tm]
2. if(parent.MyFra me)if(parent.My Frame.document)
if(parent.MyFra me.document.get ElementById("My Input"))
can and should be expressed as
if (parent.frames['MyFrame']
&& parent.MyFrame. document
setTimeout("myF oo()",1000);ret urn;
Seriously think about that for a minute! You set probably thousands of
timeouts here (since it runs in a tight loop) to go off 1000 milliseconds
(1 second) later. The faster the CPU is, the more timeouts will go off at
approximately the _same_ time. And then it is not over because each of
these thousands of timeouts will set even more timeouts _each_ which will
set more timeouts which ... as myFoo() always called again. That will be
probably 1 million timeouts at the least! A sure way to cripple the user's
system beyond repair.
You sir, who calls himself Dr Clue, have no clue at all. Or you have a
clue and deliberately want harm others, who knows. The fact is: You are
dangerous. You should be condemned to have no computer access at all
for a very long time. FOAD!
PointedEars
> if (parent.frames['MyFrame'] && parent.MyFrame. document
That works great.
Many thanks
Stefan
Stefan Mueller wrote: if (parent.frames['MyFrame']
&& parent.MyFrame. document
That works great.
However, the timeout-in-tight-loop problem remains.
In my UFPDB[1], I am using something similar to the following
to ensure availability of a method in another frame.
function makeBanner()
{
var f;
if (parent
&& (f = parent.frames)
&& (f = f['ufpdb_banner'])
&& typeof f.makeLeftBanne r == "function")
{
if (typeof makeBanner.time out != "undefined" )
{
window.clearTim eout(makeBanner .timeout);
delete makeBanner.time out;
}
f.makeLeftBanne r(...);
}
else
{
makeBanner.time out = window.setTimeo ut("makeBanner( );", 250);
}
}
makeBanner();
Your target of testing availability of a DOM element is not much
different to that.
As you can see, in contrast to the harmful solution provided by
"Dr Clue", I do not not set the timeout in a tight loop and I
set it only if necessary, hence there is only one timeout to
go off and if no longer needed, it is properly cleared.
PointedEars
___________
[1] <http://www.pointedears .de/ufpdb/> (always under construction,
so please don't bother with bug reports until further notice)
Matt Kruse wrote: Thomas 'PointedEars' Lahn wrote: can and should be expressed as
if (parent.frames['MyFrame']
&& parent.MyFrame. document
No it shouldn't.
Try:
if (parent.frames['MyFrame'] && parent.frames['MyFrame'].document)
Yes, yes, I dare forgetting to change one property accessor which bears
almost no meaning in that context regarding any known user agent, if that.
It's your nitpick day today? Then let me nitpick, too: your code as-is is
neither efficient nor does it qualify as a reliable solution regarding the
OP's request as the tests for the host objects, especially the target
element object, are missing. It should read
var o;
if (typeof window != "undefined"
&& (o = window.parent)
&& (o = o.frames)
&& (o = o['MyFrame'])
&& (o = o.document)
&& (o = o.forms)
&& (o = o['MyForm'])
&& (o = o.elements)
&& (o = o['MyInput'])
&& typeof o.value != "undefined" )
{
// access `o.value' here
}
Get a life :-b
PointedEars
Thomas 'PointedEars' Lahn wrote: Matt Kruse wrote: Thomas 'PointedEars' Lahn wrote: can and should be expressed as
if (parent.frames['MyFrame']
&& parent.MyFrame. document
Try:
if (parent.frames['MyFrame'] && parent.frames['MyFrame'].document)
Yes, yes, I dare forgetting to change one property accessor which
bears almost no meaning in that context regarding any known user
agent, if that.
Your original syntax had a potential name collision with a global variable
named "MyFrame", which very well might be a realistic case, and very well
might cause a problem.
My correction was to that potential problem, and not intended to be a
complete solution for the OP.
--
Matt Kruse http://www.JavascriptToolbox.com http://www.AjaxToolbox.com
> if (parent.frames['MyFrame'] && parent.frames['MyFrame'].document)
I'm doing my tests exactly like you told me and it works perfect.
But I not really understand why to do
if (parent.MyFrame && parent.MyFrame. document &&
parent.MyFrame. document.MyForm && parent.MyFrame. document.MyForm .MyInput) {
Why can't I just do
if (parent.MyFrame .document.MyFor m.MyInput) {
?
I know it doesn't work but I really don't understand that because I think
that in both cases if the MyInput text box doesn't exist
(parent.MyFrame .document.MyFor m.MyInput) returns false.
Stefan
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