Fire event at a certain time of the day

Question

Is it possible with javascript (jQuery solutions are fine too) to fire an event/call a function at certain times of the day e.g.

call myFunctionA at 10:00

ca

Answer 1

I ran into this problem and came up with a more elaborate solution. The basic idea is the same as in the other answers: use setTimeout() with an interval from now to the desired time point.

Other details used here: if the time point is in the past, schedule it for tomorrow (at time point + 24 hours). Trigger the function at the given time point every day from now using setInterval(). Note: DST is not considered here.

Input params:
time = '16:00';
triggerThis = function() { alert('this was triggered'); };

  scheduleWarning(time, triggerThis) {

    // get hour and minute from hour:minute param received, ex.: '16:00'
    const hour = Number(time.split(':')[0]);
    const minute = Number(time.split(':')[1]);

    // create a Date object at the desired timepoint
    const startTime = new Date(); startTime.setHours(hour, minute);
    const now = new Date();

    // increase timepoint by 24 hours if in the past
    if (startTime.getTime() < now.getTime()) {
      startTime.setHours(startTime.getHours() + 24);
    }

    // get the interval in ms from now to the timepoint when to trigger the alarm
    const firstTriggerAfterMs = startTime.getTime() - now.getTime();

    // trigger the function triggerThis() at the timepoint
    // create setInterval when the timepoint is reached to trigger it every day at this timepoint
    setTimeout(function(){
      triggerThis();
      setInterval(triggerThis, 24 * 60 * 60 * 1000);
    }, firstTriggerAfterMs);

  }