Execute callback on time (schedule)

scheduleWarning.js

/***
Usage:
scheduleWarning('05:00:00',()=>console.log(new Date().toString())
*/
function scheduleWarning(time, triggerThis, adjust){
    const ensureValidNum = (v, d, min, max) => {
        if (!(typeof v === 'number' && !isNaN(v))) {
            return d;
        }
        if (!(v >= min && v <= max)) { return d; }
        
        return v;
    }
    
    const parts = time.split(':');
    // get hour and minute from hour:minute param received, ex.: '16:00'
    const hour = ensureValidNum(parts[0], 0, 0, 23)
    const minute = ensureValidNum(parts[1], 0, 0, 59)
    const seconds = ensureValidNum(parts[2], 0, 0, 59);
    
    // create a Date object at the desired timepoint
    const startTime = new Date(); 
    startTime.setHours(hour, minute, seconds);
    let 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(() => {
      triggerThis();
      setInterval(triggerThis, 24 * 60 * 60 * 1000);
    }, firstTriggerAfterMs);

  }