checks if a given day is an occurance in a recurrence rule

isDayAnOccurance.js

export function isDayAnOccurance(day, recurrenceRule) {
  const rule = RRule.fromString(recurrenceRule);

  // Convert all dates into UTC before comparison
  const today = moment(day).utc().startOf('day');
  const nextOccurrence = moment(rule.after(today, true)).utc();
  const match = moment(nextOccurrence).isSame(today, 'day');

  return match;
}