The following computational property returns an array of days of each month:

getDays(){
  return new Array(this.currentMonth.clone().daysInMonth())
    .fill(null)
    .map((x, i) => this.currentMonth
      .clone()
      .startOf('month')
      .add(i, 'days')
    );
}

But how can I put days from the current date in the active month, but at the same time fill in the next month completely from the first day?

That's what I want:

current month - March

days of March - [today(March 14) ... last day of month]

Next month - April

days of March - [first day of month ... last day of month]