Timer on webpages

[David]

Hi,

Im not sure where to find all the documentation i need for this? I need
to timer since a start button has been pushed, and show a counter on a
page. If they click stop i want to keep the time, and carry on
incrementing it if they click start again.

Any suggestions on code, or reference material for this?

Thanks for all the help

David

[Ben C]

On 2006-04-29, David <da************ @gmail.com> wrote:

Hi,

Im not sure where to find all the documentation i need for this? I need
to timer since a start button has been pushed, and show a counter on a
page. If they click stop i want to keep the time, and carry on
incrementing it if they click start again.

Any suggestions on code, or reference material for this?

Tricky one. I can't think of a way except using setInterval, with an
interval of about a second. In the callback you update the counter,
animation, etc., and increment a variable that counts how many seconds have
elapsed.

[Randy Webb]

Ben C said the following on 4/29/2006 11:53 AM:

On 2006-04-29, David <da************ @gmail.com> wrote:

Hi,

Im not sure where to find all the documentation i need for this? I need
to timer since a start button has been pushed, and show a counter on a
page. If they click stop i want to keep the time, and carry on
incrementing it if they click start again.

Any suggestions on code, or reference material for this?
Tricky one.

Not really.
I can't think of a way except using setInterval,
There are other ways but setInterval would be the best way to update the
page itself. Not necessarily the best way to increment the counter though.
with an interval of about a second.
The resolution you used for setInterval would depend on how much
resource you would be willing to use and how accurate you wanted the
counter time wise.
In the callback you update the counter, animation, etc.,
and increment a variable that counts how many seconds have elapsed.

I don't agree with that one. Incrementing a variable would lead to
inaccuracies in the total. Just start with a Date object and compare the
current time, get the difference, and display it.

The only difference in this question and any other "running counter"
question is the Start/Stop buttons. And how you handled those would
depend, directly, on whether the OP wanted the timer to include the
Stopped time or not.

--
Randy
comp.lang.javas cript FAQ - http://jibbering.com/faq & newsgroup weekly
Javascript Best Practices - http://www.JavascriptToolbox.com/bestpractices/

[Dr John Stockton]

JRS: In article <mM************ *************** ***@comcast.com >, dated
Sat, 29 Apr 2006 14:34:28 remote, seen in news:comp.lang. javascript,
Randy Webb <Hi************ @aol.com> posted :

In the callback you update the counter, animation, etc.,
and increment a variable that counts how many seconds have elapsed.

I don't agree with that one. Incrementing a variable would lead to
inaccuracies in the total. Just start with a Date object and compare the
current time, get the difference, and display it.

Using a Date Object to indicate duration will be unreliable in systems
where the clock is being automatically synchronised from time to time.

Using a Date Object naively to indicate duration will be unreliable when
the season changes between Summer and Winter.

--
© John Stockton, Surrey, UK. ?@merlyn.demon. co.uk Turnpike v4.00 MIME. ©
Web <URL:http://www.merlyn.demo n.co.uk/> - w. FAQish topics, links, acronyms
PAS EXE etc : <URL:http://www.merlyn.demo n.co.uk/programs/> - see 00index.htm
Dates - miscdate.htm moredate.htm js-dates.htm pas-time.htm critdate.htm etc.

[Randy Webb]

Dr John Stockton said the following on 4/29/2006 5:25 PM:

JRS: In article <mM************ *************** ***@comcast.com >, dated
Sat, 29 Apr 2006 14:34:28 remote, seen in news:comp.lang. javascript,
Randy Webb <Hi************ @aol.com> posted :

In the callback you update the counter, animation, etc.,
and increment a variable that counts how many seconds have elapsed. I don't agree with that one. Incrementing a variable would lead to
inaccuracies in the total. Just start with a Date object and compare the
current time, get the difference, and display it.

Using a Date Object to indicate duration will be unreliable in systems
where the clock is being automatically synchronised from time to time.

If your app is that time critical, then you would know whether that was
happening or not and if you didn't allow for it then you get what you
deserve.
Using a Date Object naively to indicate duration will be unreliable when
the season changes between Summer and Winter.

And naively assuming that most business applications are being used on a
Saturday night at 2AM is indeed naive.

--
Randy
comp.lang.javas cript FAQ - http://jibbering.com/faq & newsgroup weekly
Javascript Best Practices - http://www.JavascriptToolbox.com/bestpractices/

[RobG]

Randy Webb wrote:

Dr John Stockton said the following on 4/29/2006 5:25 PM:

JRS: In article <mM************ *************** ***@comcast.com >, dated
Sat, 29 Apr 2006 14:34:28 remote, seen in news:comp.lang. javascript,
Randy Webb <Hi************ @aol.com> posted :

In the callback you update the counter, animation, etc., and
increment a variable that counts how many seconds have elapsed.
I don't agree with that one. Incrementing a variable would lead to
inaccuracies in the total. Just start with a Date object and compare
the current time, get the difference, and display it.

Using a Date Object to indicate duration will be unreliable in systems
where the clock is being automatically synchronised from time to time.

If your app is that time critical, then you would know whether that was
happening or not and if you didn't allow for it then you get what you
deserve.

Absolutely, so worth mentioning.

Using a Date Object naively to indicate duration will be unreliable when
the season changes between Summer and Winter.

And naively assuming that most business applications are being used on a
Saturday night at 2AM is indeed naive.

That is not naive at all - many businesses that have a production
process have shift work. I've frequently been involved in projects with
24hr shifts, 7 days per week over many months. That is common on
projects such as those that use very expensive CAD equipment, say a
major construction project.
--
Rob

[Randy Webb]

RobG said the following on 4/29/2006 10:54 PM:

Randy Webb wrote:

Dr John Stockton said the following on 4/29/2006 5:25 PM:

JRS: In article <mM************ *************** ***@comcast.com >, dated
Sat, 29 Apr 2006 14:34:28 remote, seen in news:comp.lang. javascript,
Randy Webb <Hi************ @aol.com> posted :
> In the callback you update the counter, animation, etc., and
> increment a variable that counts how many seconds have elapsed.
I don't agree with that one. Incrementing a variable would lead to
inaccuracies in the total. Just start with a Date object and compare
the current time, get the difference, and display it.

Using a Date Object to indicate duration will be unreliable in systems
where the clock is being automatically synchronised from time to time.

If your app is that time critical, then you would know whether that
was happening or not and if you didn't allow for it then you get what
you deserve.

Absolutely, so worth mentioning.

Using a Date Object naively to indicate duration will be unreliable when
the season changes between Summer and Winter.

And naively assuming that most business applications are being used on
a Saturday night at 2AM is indeed naive.

That is not naive at all - many businesses that have a production
process have shift work. I've frequently been involved in projects with
24hr shifts, 7 days per week over many months. That is common on
projects such as those that use very expensive CAD equipment, say a
major construction project.

True, but that falls into the first category. That is a time critical
application and if you don't take care to account for it then you, well,
deserve what you get :)

But, your point is valid.

But, most sites that have a count-down/up timer are not business apps.
Some are, but most aren't. Probably a quiz type site that the OP has.

--
Randy
comp.lang.javas cript FAQ - http://jibbering.com/faq & newsgroup weekly
Javascript Best Practices - http://www.JavascriptToolbox.com/bestpractices/

[Dr John Stockton]

JRS: In article <EN************ *************** ***@comcast.com >, dated
Sat, 29 Apr 2006 20:56:16 remote, seen in news:comp.lang. javascript,
Randy Webb <Hi************ @aol.com> posted :

Dr John Stockton said the following on 4/29/2006 5:25 PM:

Using a Date Object naively to indicate duration will be unreliable when
the season changes between Summer and Winter.

And naively assuming that most business applications are being used on a
Saturday night at 2AM is indeed naive.

It would be; but we should not be concerned just with "most" here; and
it is naive to assume that the clock necessarily changes at 2AM.

Then just consider all the Muslim and Jewish businessmen; the businesses
that run 24/7/366; the travellers who keep there portables set to Home
Time, ...

--
© John Stockton, Surrey, UK. ?@merlyn.demon. co.uk Turnpike v4.00 MIME. ©
Web <URL:http://www.merlyn.demo n.co.uk/> - w. FAQish topics, links, acronyms
PAS EXE etc : <URL:http://www.merlyn.demo n.co.uk/programs/> - see 00index.htm
Dates - miscdate.htm moredate.htm js-dates.htm pas-time.htm critdate.htm etc.

[Randy Webb]

Dr John Stockton said the following on 4/30/2006 5:50 PM:

JRS: In article <EN************ *************** ***@comcast.com >, dated
Sat, 29 Apr 2006 20:56:16 remote, seen in news:comp.lang. javascript,
Randy Webb <Hi************ @aol.com> posted :

Dr John Stockton said the following on 4/29/2006 5:25 PM:

Using a Date Object naively to indicate duration will be unreliable when
the season changes between Summer and Winter.

And naively assuming that most business applications are being used on a
Saturday night at 2AM is indeed naive.

It would be; but we should not be concerned just with "most" here; and
it is naive to assume that the clock necessarily changes at 2AM.

And this entire scenario falls into the part of my reply that you snipped:

<quote>
If your app is that time critical, then you would know whether that was
happening or not and if you didn't allow for it then you get what you
deserve.
</quote>
Then just consider all the Muslim and Jewish businessmen; the businesses
that run 24/7/366; the travellers who keep there portables set to Home
Time, ...

I am not sure what being Muslim or Jewish has to do with that.

But, it still falls into the first category.

--
Randy
comp.lang.javas cript FAQ - http://jibbering.com/faq & newsgroup weekly
Javascript Best Practices - http://www.JavascriptToolbox.com/bestpractices/

[Dr John Stockton]

JRS: In article <O6************ *************** ***@comcast.com >, dated
Sun, 30 Apr 2006 22:37:29 remote, seen in news:comp.lang. javascript,
Randy Webb <Hi************ @aol.com> posted :

Dr John Stockton said the following on 4/30/2006 5:50 PM:

JRS: In article <EN************ *************** ***@comcast.com >, dated
Sat, 29 Apr 2006 20:56:16 remote, seen in news:comp.lang. javascript,
Randy Webb <Hi************ @aol.com> posted :

Dr John Stockton said the following on 4/29/2006 5:25 PM:

Using a Date Object naively to indicate duration will be unreliable when
the season changes between Summer and Winter.
And naively assuming that most business applications are being used on a
Saturday night at 2AM is indeed naive.

It would be; but we should not be concerned just with "most" here; and
it is naive to assume that the clock necessarily changes at 2AM.

And this entire scenario falls into the part of my reply that you snipped:

<quote>
If your app is that time critical, then you would know whether that was
happening or not and if you didn't allow for it then you get what you
deserve.
</quote>

Don't assume that questioners and readers are as intelligent as you
think you are.

Then just consider all the Muslim and Jewish businessmen; the businesses
that run 24/7/366; the travellers who keep there portables set to Home
Time, ...

I am not sure what being Muslim or Jewish has to do with that.

Knowing nothing about other cultures is part of being a WASP, no doubt.
FYI, those people do not regard Sunday as the ordained Day of Rest.

--
© John Stockton, Surrey, UK. ?@merlyn.demon. co.uk Turnpike v4.00 MIME. ©
Web <URL:http://www.merlyn.demo n.co.uk/> - w. FAQish topics, links, acronyms
PAS EXE etc : <URL:http://www.merlyn.demo n.co.uk/programs/> - see 00index.htm
Dates - miscdate.htm moredate.htm js-dates.htm pas-time.htm critdate.htm etc.