Moment.js : Get first day of first week by given year

Im trying to get the first day of first week by given day

Correct results :

2017 = 2 Jan (Monday)

2016 = 4 Jan (Monday)

2015 = 1 Jan (Thursday)

2014 = 1 Jan (Wednesday)

2013 = 1 Jan (Tuesday)

I can get the first day of the year by :

moment().year(year).startOf('year') // All result is 1. jan XXXX

Then I tried : (correct)

moment().day(1).year(2017).week(1) // 2 Jan (Monday) (correct)

But when changed to 2016 : (wrong)

moment().day(1).year(2016).week(1) // 10 Jan (Sunday) (wrong)

Any know how to get correct results ? (Im open for pure JS date() also)

PS: Week number is based in Norway

Playground : https://jsfiddle.net/6sar7eb4/