Question

I am trying to create a google annotated timeline viz. For that I need to input the date of the event. The only information I have is the year & the ISO week number for the event. Is there a way in Javascript to create a Date object using just the year & week number? I googled it but did not come across any feasible solution.

Thanks for the help!

Answer 1

ISO weeks start on Monday

If 1 January is on a Monday, Tuesday, Wednesday or Thursday, it is in week 01.
If 1 January is on a Friday, Saturday or Sunday, it is in week 52 or 53 of the previous year

Date.weekofYear= function(s){
    var yw= s.split(/\D+0?/),
    weeks= 7*yw[1]-7,
    date1= new Date(yw[0], 0, 1),
    day1= date1.getDay(),
    incr= (day1> 0 && day1<5)? -1: 1;
    if(yw[2]) weeks+= (+yw[2])-1;// optional day in week

    while(date1.getDay()!= 1){
        date1.setDate(date1.getDate()+incr);
    }
    date1.setDate(date1.getDate()+weeks);
    return date1;
}

Date.weekofYear('2010-20').toLocaleDateString()
// (use UTC methods to start the weeks on Greenwich instead of local time)
/*  returned value: (String)
Monday, May 17, 2010
*/