Which option is better to execute window.setTimeout and why?
Option A:
window.setTimeout(somefunc,0);
Option B:
window.setTimeout(somefunc,n); //n may be any number >0
Thanks.
views:
348answers:
5
+1
A:
Option A will simply call somefunc with the additional overhead of needlessly calling setTimeout (since your second parameter means 0 milliseconds of delay). Option B is for if you intend to have a delay prior to the execution of somefunc. Could you elaborate a bit please, or does this answer your question?
karim79
2010-03-04 01:33:56
I have few frames(1~6) and I make those frames editable using designmode="on". After that I set contents (from database) in those frames. But unfortunately, contents are not always loaded.
Hoque
2010-03-04 01:59:55
+1
A:
It depends on what you want to do.
setTimeout(somefunc,0) is not so different with just calling somefunc
(but I guess .setTimeout(somefunc,0) will finish current block first and then called somefunc)
If you need to wait browser rendering, and run somefunc after that, use window.onload or jQuery's $(document).ready
S.Mark
2010-03-04 01:34:51
Instead of using somefunc() if I use setTimeout(somefunc,n) , then somefunc executes.It executes whether I put the delay "0" or any other value.
Hoque
2010-03-04 01:55:04
@Hoque, the 2nd parameter just determines how long the "new thread" waits before firing somefunc(). If you don't "need" a new thread... just call somefunc()
scunliffe
2010-03-04 02:01:32
true, it is single threaded... that's why "new thread" was in quotes. setTimeout and setInterval basically allow you run 2 or more bits of code simutaneously.
scunliffe
2010-03-04 03:56:28
if single thread, then what will happen to the old thread? Will the old thread die and new thread will start?
Hoque
2010-03-04 04:00:11
A:
window.setTimeout(somefunc,0);
will run somefunc right away (but won't wait for a return value before continuing)
window.setTimeout(somefunc,n);
will wait n milliseconds before running somefunc (but won't wait for it to start or return before continuing)
or if you call somefunc() without the timeout it will run somefunc but wait for it to finish before continuing.
consider setTimeout to be like "starting" a new thread.
scunliffe
2010-03-04 01:40:58
"won't wait for a return value", what is the return value. I am not clear about that. Would you mind to tell me more about the return value?
Hoque
2010-03-04 02:02:33
any time you call a function it can return a value. e.g. `var name = getUserName();` could set `name` with a value returned from `getUserName()`. Even if you don't want or care to return a value... code after your call to `somefunc()` would not execute until somefunc was finished. By using setTimeout, you tell the browser you don't want to wait... continue executing code... and run somefunc() after `n` milliseconds.
scunliffe
2010-03-04 03:53:06
So far I know that Javascript is single threaded. "consider setTimeout to be like "starting" a new thread." -then will it be multi-threaded?Thanks.
Hoque
2010-03-04 04:09:37
+1
A:
The thing about a timeout or an interval, they always wait for the current thread to run out before they execute their own function- even if you put it in the first line.
var color='white';
setTimeout(function(){alert(color+' from timeout')}, 0);
for(var i=0;i<100001;++i){
if(i=100000)alert(color='green');
}
alert(color='red')
kennebec
2010-03-04 02:40:00
Nice example, if I have two setTimeout, then which will be executed first?
Hoque
2010-03-04 04:14:25
A:
I recall having some browser issues when using setTimeout (func, 0) so now I do setTimeout (func, 1) whenever I want to have the shortest delay. Note that for most (all?) browsers the real shortest delay is some number n > 1 (definately n > 0 and probably n < 50).
Which browser I was having issues with I don't remember.
trinithis
2010-03-04 03:00:33