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Re: How to write a browser based timer

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In comp.lang.javascript message <bnmdk7dbd04crei6qnaip7mosmesh8vkc8@4ax.
com>, Thu, 23 Feb 2012 16:38:03, Gene Wirchenko <genew@ocis.net> posted:

>On Thu, 23 Feb 2012 19:31:27 +0000, Dr J R Stockton
><reply1208@merlyn.demon.co.uk> wrote:
>
>[snip]
>
>>The answer, IMHO, is to use setInterval.  I'm not sure what happens if
>>one calls for an interval of one second and, after a while, keeps the
>>CPU very busy for a few seconds - does one get a burst of late
>>setInterval handler calls, or are some lost?  And what if, after
>>starting with setInterval, the machine is put into standby for a while?
>>But with setInterval, delays of substantially under a second in making
>>one handler call do not accumulate, as they would with simple repeated
>>setTimeout (Func, /const/)
>
>     I suspect that the next interval is set as part of the previous
>one firing:
>
>     Catch that an interval has expired:
>        Set next interval.
>        Do what is supposed to be done with an fired interval.

You may think that.  But I prefer to believe MDN; or, if something is
important to me, the results of tests.  St Luke: Chapter 10, Verse 37,
tail; consider the implications of
<https://developer.mozilla.org/en/window.setInterval> "Dangerous usage"


>>To allow as best one can for such possibilities, the OP should NOT count
>>those handler calls for a measure of time, but should call new Date() to
>>get the time in milliseconds, from which simple arithmetic will get the
>>minutes, seconds, and maybe fractional part to display.
>
>     Quite.
>
>>However, the valid objections to a wait loop along the lines of
>>        while (new Date()<EndTime) { ... }
>>are fewer than commonly thought.  A simple loop calculating the date of
>>Gregorian Easter Sunday for a full cycle or more takes a significant
>>while, but with at least some browsers the machine is still adequately
>>responsive.
>
>     I do not agree.  On a system doing only one thing (as far as the
>user is concerned?), that may be fine, but with multiple things going,
>no.

As above.  A sensible operating system, operating on adequate hardware,
will not allow a single user process to exclude everything else.  But
using timeouts is nicer.

There seems, though, to be a related fault in at least some browser
implementations :   while (true) alert("")   cannot be interrupted
except by killing at least the tab, maybe the window, maybe all windows
of that browser.

-- 
 (c) John Stockton, nr London, UK. ?@merlyn.demon.co.uk  Turnpike 6.05  WinXP.
 Web  <http://www.merlyn.demon.co.uk/> - FAQ-type topics, acronyms, and links.
 Command-prompt MiniTrue is useful for viewing/searching/altering files. Free,
 DOS/Win/UNIX now 2.0.6; see <URL:http://www.merlyn.demon.co.uk/pc-links.htm>.

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Thread

How to write a browser based timer " Cal Who" <CalWhoNOSPAM@roadrunner.com> - 2012-02-21 15:50 -0500
  Re: How to write a browser based timer Scott Sauyet <scott.sauyet@gmail.com> - 2012-02-21 13:04 -0800
    Re: How to write a browser based timer Gene Wirchenko <genew@ocis.net> - 2012-02-21 13:45 -0800
      Re: How to write a browser based timer "Evertjan." <exjxw.hannivoort@interxnl.net> - 2012-02-21 22:40 +0000
        Re: How to write a browser based timer Gene Wirchenko <genew@ocis.net> - 2012-02-21 15:04 -0800
          Re: How to write a browser based timer "Evertjan." <exjxw.hannivoort@interxnl.net> - 2012-02-21 23:27 +0000
            Re: How to write a browser based timer Gene Wirchenko <genew@ocis.net> - 2012-02-21 16:08 -0800
              Re: How to write a browser based timer "Evertjan." <exjxw.hannivoort@interxnl.net> - 2012-02-22 15:41 +0000
                Re: How to write a browser based timer Gene Wirchenko <genew@ocis.net> - 2012-02-22 09:19 -0800
                Re: How to write a browser based timer "Evertjan." <exjxw.hannivoort@interxnl.net> - 2012-02-22 21:55 +0000
                Re: How to write a browser based timer Gene Wirchenko <genew@ocis.net> - 2012-02-22 15:01 -0800
        Re: How to write a browser based timer RobG <rgqld@iinet.net.au> - 2012-02-21 18:18 -0800
          Re: How to write a browser based timer Dr J R Stockton <reply1208@merlyn.demon.co.uk> - 2012-02-23 19:31 +0000
            Re: How to write a browser based timer Gene Wirchenko <genew@ocis.net> - 2012-02-23 16:38 -0800
              Re: How to write a browser based timer Dr J R Stockton <reply1208@merlyn.demon.co.uk> - 2012-02-25 20:29 +0000
                Re: How to write a browser based timer "Evertjan." <exjxw.hannivoort@interxnl.net> - 2012-02-26 23:02 +0000
      Re: How to write a browser based timer Dr J R Stockton <jrs@merlyn.demon.co.uk> - 2012-02-22 18:51 +0000
    Re: How to write a browser based timer " Cal Who" <CalWhoNOSPAM@roadrunner.com> - 2012-02-23 10:23 -0500
      Re: How to write a browser based timer Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-02-23 22:13 +0100
        Re: How to write a browser based timer Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-02-24 09:41 +0100

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