whats wrong with this wait function?

[Rasmus Grøndahl Olsen]

I have tried to write a wait function but it seems like it will not brake
the while loop. I tried two different solutions.
Can anyone tell me what I am doing wrong, and come with another suggestion?
If I call the function like this: wait(500); it should wait 500ms right?

function wait(time) {
while(1){
setTimeout("bre ak;",time);
}
}

function wait(time) {
var flag=0;
while(flag=0){
setTimeout("fla g=1;",time);
}
}

[Lasse Reichstein Nielsen]

Re: whats wrong with this wait function?

"Rasmus Grøndahl Olsen" <zordid@bigfoot .com> writes:
[color=blue]
> I have tried to write a wait function but it seems like it will not brake
> the while loop. I tried two different solutions.
> Can anyone tell me what I am doing wrong, and come with another suggestion?
> If I call the function like this: wait(500); it should wait 500ms right?[/color]

No.

setTimeout doesn't dealy execution. It schedules the argument code to
be executed at a later time, and then continues with the current code.
[color=blue]
> function wait(time) {
> while(1){
> setTimeout("bre ak;",time);
> }
> }[/color]

The code "break" is not executed as part of the current context, but as
fresh code in the global context. It has no way of breaking a while
loop that it is not inside.
[color=blue]
> function wait(time) {
> var flag=0;
> while(flag=0){
> setTimeout("fla g=1;",time);
> }
> }[/color]

This could work, except that the flag variable is local, and the
scheduled code is executed in a different context.

No need to make more than one setTimeout.

Try either:

var flag = false;
function wait(time) {
setTimeout("fla g = true",time)
while(!flag){};
}

or

function wait(time) {
var flag = false;
setTimeout(func tion(){flag = true;},time);
while(!flag){};
}

In both cases, you spend all available processor power on a busy loop
that does nothing. That (called "busy waiting") is bad style in any
language.

Instead of using a wait function, you should reschedule the remainder
of your code instead.

// blah blah code
wait(500);
// blah blah more code

should be
// blah blah code
setTimeout(func tion(){
// blah blah more code
},500);

Ofcourse, if you plan on returning a result, it will need more fixing.

/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.'

[Evertjan.]

Re: whats wrong with this wait function?

Rasmus Grøndahl Olsen wrote on 27 okt 2003 in comp.lang.javas cript:
[color=blue]
> I have tried to write a wait function but it seems like it will not
> brake the while loop. I tried two different solutions.
> Can anyone tell me what I am doing wrong, and come with another
> suggestion? If I call the function like this: wait(500); it should
> wait 500ms right?
>
> function wait(time) {
> while(1){
> setTimeout("bre ak;",time);
> }
>}
>
> function wait(time) {
> var flag=0;
> while(flag=0){
> setTimeout("fla g=1;",time);
> }
>}
>[/color]

That is not the way JS works, even with while(flag==0)

try this:

<script>

function main() {
// do this
// do that
setTimeout("mai n2()",1000); // 1 second
}
function main2() {
// do this
// do that
setTimeout("mai n3()",2000); // 2 seconds
}
function main3() {
// do this
// do that
setTimeout("mai n4()",60000); // 1 minute
}
function main4() {
// do this
// do that
setTimeout("mai n2()",2000); // 2 seconds, then loop to main2
}

main()

</script>



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Evertjan.
The Netherlands.
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