Problem with Focus... Help needed.

**Michael Winter** · Jul 23 '05, 01:05 PM

Re: Problem with Focus... Help needed.

On 16 Aug 2004 08:51:56 -0700, Nitin <nitin.thakur@u bs.com> wrote:
[color=blue]
> I have created function to check date and time. at the time of
> execution, if date is left empty the function returns the error
> message but then the focus goes to next field. Next filed is for time
> and there is also a check on that. If time is empty return error
> message. Again the explorer returns error message and then shifts the
> focus to date field, again error message and focus goes to time and
> this story goes on and on, untill browser is killed. can somebody help
> me in debuggin this script.[/color]

I don't believe that there's a problem with your script (I haven't taken a
close look), I think it's your HTML.

[snip]
[color=blue]
> <INPUT TYPE="text" NAME="startdate " VALUE="" SIZE=8 MAXLENGTH=8
> ONBLUR="return CheckDate(this) "> [...][/color]

The blur event is fired *every* time the control loses focus. So:

1) Click or tab to next control (B)
2) Current control (A) loses focus (event fires) and control B gains focus.
3) Validation fails, alert shows error message and user dismisses it.
4) Control A requests focus.
5) Control B loses focus and control A gains focus.
6) Validation for B fails, alert shows, and user dismisses it.
7) B requests focus.
8) Repeat from 3.

The solution is to use the change event; the event will only fire if the
value has actually changed. The user can skip a field without changing it,
and you won't end up in a loop. Of course, this means that you'll need to
validate the form at submission in case the user never enters a value.

Hope that helps,
Mike

--
Michael Winter
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**Richard Cornford** · Jul 23 '05, 01:05 PM

Re: Problem with Focus... Help needed.

Michael Winter wrote:[color=blue]
> Nitin wrote:[/color]
<snip>[color=blue][color=green]
>> <INPUT TYPE="text" NAME="startdate " VALUE="" SIZE=8
>> MAXLENGTH=8 ONBLUR="return CheckDate(this) "> [...][/color]
>
> The blur event is fired *every* time the control loses focus. So:
>
> 1) Click or tab to next control (B)
> 2) Current control (A) loses focus (event fires) and control B
> gains focus. 3) Validation fails, alert shows error message
> and user dismisses it.
> 4) Control A requests focus.
> 5) Control B loses focus and control A gains focus.
> 6) Validation for B fails, alert shows, and user dismisses it.
> 7) B requests focus.
> 8) Repeat from 3.[/color]
<snip>

The same never ending loop is the consequence but in practice when an
alert is put up the focus goes to the OK button on the alert, so control
B loses focus at that point. Assuming that it has actually been passed
focus at that point. I have a recollection of a browser where the onblur
code is executed prior to the focusing of the next control, so when the
onblur code re-focuses the first control the browser then goes on to do
what it was planning anyway and focuses the next control, re-blurring
the first.

I too would recommend not attempting validation with onblur events.

Richard.

**Michael Winter** · Jul 23 '05, 01:05 PM

Re: Problem with Focus... Help needed.

On Mon, 16 Aug 2004 18:28:31 +0100, Richard Cornford
<Richard@litote s.demon.co.uk> wrote:

[snip]
[color=blue]
> The same never ending loop is the consequence but in practice when an
> alert is put up the focus goes to the OK button on the alert, so control
> B loses focus at that point. [...][/color]

I assumed that it would, but it doesn't appear to fire an event. At least
not in my tests with Opera when an event is being executed. I didn't test
with other browsers as Opera was sufficient for building the sequence I
wrote.
[color=blue]
> I too would recommend not attempting validation with onblur events.[/color]

That's more important, anyway.

Mike

--
Michael Winter
Replace ".invalid" with ".uk" to reply by e-mail

**Dr John Stockton** · Jul 23 '05, 01:06 PM

Re: Problem with Focus... Help needed.

JRS: In article <ff21db84.04081 60751.7d4e8f5b@ posting.google. com>,
dated Mon, 16 Aug 2004 08:51:56, seen in news:comp.lang. javascript,
Nitin <nitin.thakur@u bs.com> posted :[color=blue]
>
>I have created function to check date and time.[/color]

One presumes that you are paid per yard of code; a much shorter date
(and time) validator can be found via the FAQ : see below.

Also see the recent thread here "Multiple Datepicker".

You can I think solve your perceived problem by validating onChange
rather than onBlur; but it would be better IMHO to validate when the
user signals that data entry is completed.

When posting code to News, it is your duty not to allow the system to
wrap your code lines - anyway, you indent in units which are too large
for convenience.

HTML should also be indented to show structure, if people are to be
expected to read it.

You seem to ask for the time in GMT; the date also should be in GMT;
then, for consistency, var longYear= now.getYear();
should probably use getUTCyear()

--
© John Stockton, Surrey, UK. ?@merlyn.demon. co.uk Turnpike v4.00 IE 4 ©
<URL:http://www.jibbering.c om/faq/> JL/RC: FAQ of news:comp.lang. javascript
<URL:http://www.merlyn.demo n.co.uk/js-index.htm> jscr maths, dates, sources.
<URL:http://www.merlyn.demo n.co.uk/> TP/BP/Delphi/jscr/&c, FAQ items, links.

Problem with Focus... Help needed.

Problem with Focus... Help needed.

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