Date utils - endOfDate

[PSTA]

Hi,
I’m using date.endOfDate this way:

getEndDateOfYear (inputDate) {
    if (!date.isValid(inputDate)) {
      inputDate = this.getDate()
    }
    return date.endOfDate(newDate, 'year')
  }

where inputDate value is for example : ‘Fri Sep 01 2017 00:00:00 GMT+0200 (Central Europe Daylight Time)’

I found that output value of my method is ‘Sat Dec 30 2017 23:59:59 GMT+0100 (Central Europe Standard Time)’
Is it correct? Because December has always 31 days… or is problem on my side?

Thx in advance
Petr

[s.molinari]

Where did newDate come from?

Scott