Trouble using setTimeout/setInterval

[Weston C]

In the course of trying to build a simple clock, I've run into a problem
using the setInterval (and setTimeout) function.

http://weston.canncentral.org/misc/tkeep/tkeep.html

http://weston.canncentral.org/misc/tkeep/tkeep.jss

function fieldToClock(fi eldId)
{
var field = document.getEle mentById(fieldI d);
alert("Starting a clock in text field " + fieldId + "(" + field
+ ")");
codeSnippet = "clockUpdat e(" + fieldId + ")";
setInterval(clo ckUpdate(fieldI d),1000);
//setInterval(cod eSnippet,1000);
//setInterval("ev al(\"" + codeSnippet + "\")",1000) ;
}

function clockUpdate(fie ldId)
{
field = document.getEle mentById(fieldI d);
field.value = date2timestr(ne w Date());
}

The problem line is the setInterval line, and it seems to have something
to do with the fact I want to pass the function clockUpdate an argument
(I don't want to specify a single text element to be associated with the
display of the clock. Ideally, I'd like to be able to call the function
"fieldToClo ck" with the id of any text field in the document and turn it
into a clock).

The two commented out lines are other approaches I've applied. The first
approach yields the error:

Error: useless setInterval call (missing quotes around argument?)
Source File: http://weston.canncentral.org/misc/tkeep/tkeep.jss
Line: 6

The second/third approach yeild:

Error: clock_STF is not defined
Source File: http://weston.canncentral.org/misc/tkeep/tkeep.jss
Line: 7

Except this error is repeated every 1000 seconds. :)

Any ideas?

Thanks,

Weston





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[Lasse Reichstein Nielsen]

Re: Trouble using setTimeout/setInterval

Weston C <west8on[at]cann8central.Re moveEights.org> writes:
[color=blue]
> In the course of trying to build a simple clock, I've run into a problem
> using the setInterval (and setTimeout) function.[/color]
[color=blue]
> var field = document.getEle mentById(fieldI d);[/color]
[color=blue]
> codeSnippet = "clockUpdat e(" + fieldId + ")";[/color]

So, fieldId is a string. Say it is the string "foobar". Then your
codeSnippet becomes the string
"clockUpdate(fo obar)"
Here, foobar is not a string, but a variable name, because the quotes
are missing. Try:
codeSnippet = "clockUpdate(\" "+fieldId+"\"); ";
[color=blue]
> setInterval(clo ckUpdate(fieldI d),1000);[/color]

Here, you call the clockUpdate function right now, and try evaluating
the result of that in one second. Try:
setInterval(fun ction(){clockUp date(fieldId);} ,1000);
or use the above codeSnippet with:[color=blue]
> //setInterval(cod eSnippet,1000);[/color]
[color=blue]
> //setInterval("ev al(\"" + codeSnippet + "\")",1000) ;[/color]

Don't use eval. Don't ever use eval (the exceptions are so rare that
you'll probably never hit them).


[color=blue]
> The two commented out lines are other approaches I've applied. The first
> approach yields the error:
>
> Error: useless setInterval call (missing quotes around argument?)
> Source File: http://weston.canncentral.org/misc/tkeep/tkeep.jss
> Line: 6[/color]

Yes, the return value of clockUpdate is undefined. It is useless to
delay "undefined" for one second.
[color=blue]
> The second/third approach yeild:
>
> Error: clock_STF is not defined
> Source File: http://weston.canncentral.org/misc/tkeep/tkeep.jss
> Line: 7[/color]

Ah, the content of your string is "clock_STF" . As I said above, it
is now seen without its quotes, as a variable, and there is no
variable defined by that name.

/l
--
Lasse Reichstein Nielsen - lrn@hotpop.com
DHTML Death Colors: <URL:http://www.infimum.dk/HTML/rasterTriangleD OM.html>
'Faith without judgement merely degrades the spirit divine.'