RRule not setting correct time if dtstart is set

Question

I try to make an rrule instance and then set the start date/time (dtstart) but the events get the wrong time.

1. I initialize a rrule instance with a basis rrule string: RRULE:FREQ=WEEKLY;INTERVAL=1;WKST=MO;COUNT=20
2. I set the dtstart date in the rrule.options like so: rrule.options.dtstart = new Date(Date.UTC(2019, 1, 4, 12, 30, 0))
3. I console.log rrule.all() to see the generated events. All events now have the current time instead of the time set via dtstart. It should show 12:30 instead

I made this sandbox demonstrating the problem.

Now, when I do exactly the same in rrule.js demo page, I get correct results. On this demo page, do the following to see what I mean:

These are the results:

As you can see, time of the events is set correctly!

Any advice appreciated!

Answer 1

Found the answer:

If you set distart explicitly in the constructor, then the problem is solved.

Compare these examples:

Example one: gives correct results:

const rrule = new RRule({
  freq: RRule.WEEKLY, 
  interval: 1, 
  wkst: RRule.MO, 
  count: 20,
  dtstart: new Date(Date.UTC(2019, 1, 4, 12, 30, 0))})

Example two: gives wrong results

const rrule = new RRule({
  freq: RRule.WEEKLY, 
  interval: 1, 
  wkst: RRule.MO, 
  count: 20})
rrule.options.dtstart = new Date(Date.UTC(2019, 1, 4, 14, 30, 0));

To me, this looks a bit counter intuitive because setting dtstart should always give the same result whether you set it in the constructor or set it afterwards.