I have the following code which demonstrates the difference in calling a long-running function directly from an event trigger, vs. using setTimeout().
Intended behavior:
When the first button is pressed, it appears pressed, the calculation runs for several seconds, then when the calculation finishes, the button appears depressed again and the second column changes from "not calculating yet" to "calculation done". (I won't elaborate on why that is supposed to happen; it's explained in linked answer.)
When the second button is pressed, the button depresses immediately; the second column immediately changes to "calculating..." text. When the calculation finishes several seconds later, the second column changes from "calculating..." to "calculation done".
What actually happens:
This works perfectly in Chrome (both buttons behave as expected)
This works perfectly in Internet Explorer 8
This does NOT work in Firefox (v.25) as-is. Specifically, the second button behaves 100% as the first one.
Changing the timeout in
setTimeout()from0to1has no effectChanging the timeout in
setTimeout()from0to500works
Which leaves me with a big conundrum.
According to the whole reason behind why setTimeout() works whereas lack of one doesn't, the delay should have zero effect on how things work, since setTimeout()'s main purpose is to change the queuing order here, NOT to delay things.
So, why is it not working with delay 0 or 1 on Firefox, but works as expected with delay 500 (and works with any delay on Internet Explorer 8/Chrome)?
UPDATE: In addition to source code below, I also made a JSFiddle. But for some reason JSFiddle refuses to even load on my Internet Explorer 8, so for that testing, the code below is required.
UPDATE2: Someone raised the possibility of there being an issue with configuration setting dom.min_timeout_value in Firefox. I have edited it from 4 to 0, restarted the browser, and nothing was fixed. It still fails with a timeout of 0 or 1 and succeeds with 500.
Here is my source code - I simply saved it to a HTML file on C: drive and opened in all three browsers:
<html><body>
<script src="http://code.jquery.com/jquery-1.9.1.js"></script>
<table border=1>
<tr><td><button id='do'>Do long calc - bad status!</button></td>
<td><div id='status'>Not Calculating yet.</div></td></tr>
<tr><td><button id='do_ok'>Do long calc - good status!</button></td>
<td><div id='status_ok'>Not Calculating yet.</div></td></tr>
</table>
<script>
function long_running(status_div) {
var result = 0;
for (var i = 0; i < 1000; i++) {
for (var j = 0; j < 700; j++) {
for (var k = 0; k < 200; k++) {
result = result + i + j + k;
}
}
}
$(status_div).text('calclation done');
}
// Assign events to buttons
$('#do').on('click', function () {
$('#status').text('calculating....');
long_running('#status');
});
$('#do_ok').on('click', function () {
$('#status_ok').text('calculating....');
window.setTimeout(function (){ long_running('#status_ok') }, 0);
});
</script>
</body></html>
To test, you will need to change the nested loop boundaries to 300/100/100 for Internet Explorer 8; or to 1000/1000/500 for Chrome, due to different sensitivity of "this JS is taking too long" error coupled with JavaScript engine speed.
