Question

I have a couple questions about javascript:

1. Does javascript have the capability to identify a filename with a timestamp as a name?

Similar to the Perl code below utilizing the POSIX module?

my $filepath = sprintf("/path/to/file%s.JSON",strftime("%y%m%d",localtime));

this is just an example. I would like to find file in format yy/mm/dd/hh/min

For example say I want to find a file with the name 12_11_03_15:15.json how can I do this with javascript.

1. Say I create a function that I want to trigger every 15 minutes to read the file how is this possible with javascript? I looked at setInterval() but that won’t work because it is dependent on when the browser is launched. Is it possible to schedule a function to execute every hh:00, hh:15, hh:30, hh:45?

Thank you very much in advance.

Answer 1

You can use the Date class to get information about the current time.

To schedule a function to run at a certain time, setInterval() is indeed the best choice. It seems like what you’re really looking for is a way to find out when to start the first interval such that it will fall on a quarter-hour. For that, you should again use Date to get the current time and subtract it from the next quarter-hour; you can use the resulting value with setTimeout to time the start of the first interval.

Here’s an example: http://jsfiddle.net/GSF6C/3/

var nextQuarterHour = new Date();
nextQuarterHour.setMilliseconds(0);
nextQuarterHour.setSeconds(0);

do {
   nextQuarterHour.setMinutes(nextQuarterHour.getMinutes() + 1);
} while (nextQuarterHour.getMinutes() % 15)

var millisecondsToNextQuarterHour = nextQuarterHour.getTime() - Date.now();

document.write(millisecondsToNextQuarterHour);

setTimeout(function () {
    alert("Ding!");
    setInterval(function () { alert("Dong!"); }, 15 * 60 * 1000);
}, millisecondsToNextQuarterHour);

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