How to get week numbers in month in Javascript?

Question

I need to generate year calendar with week numbers which should look like this image:

However it is not trivial to get week numbers in each month so they wouldn't overlap or be missing. I am using weekCount() function from this SO question. And for displaying calendar I have written this code:

var year = parseInt($(this).text());
     var months = {1:'leden',2:'únor',3:'březen',4:'duben',5:'květen',6:'červen',7:'červenec',8:'srpen',9:'září',10:'říjen',11:'listopad',12:'prosinec'};
     var calendar = $('<div id="summary_search_form_menu"></div>');
     calendar.offset({top:$(this).offset().top + $(this).height() + 10}).css({right: '0px'});
     var cur_week = 0;
     for (var i=1;i<=12;i++) {
       var row = $('<div class="row"></div>');
       row.append('<div class="month button dark-blue">'+months[i]+'</div>');
       var week_count = weekCount(year, i);
       for (var week=1;week<week_count;week++) {
         cur_week++;
         row.append('<div class="week button blue">'+cur_week+'</div>');
       }
       calendar.append(row);
     }
     $('body').append(calendar);

Any way how to display week numbers correctly ?

No, that's an error which I need to fix, that's why I am asking this question :-) — Frodik, Aug 27 '15 at 19:56
What if a month has 4 weeks complete and 3 extra days? What will be output weeks 4 or 5 ? — Ankit Agarwal, Aug 27 '15 at 20:01
There is a standard to week numbers, and this post pretty much nails it http://stackoverflow.com/q/6117814/575527 — Joseph, Aug 27 '15 at 20:08
@AnkitAgarwal I don't know, probably it should have 5 weeks, but then the half week should be counted only once. — Frodik, Aug 28 '15 at 16:58

score 0 · Answer 1 · answered Aug 29 '15 at 04:49

OK, I have finally solved this on my own. In case somebody would find it helpful, I post my final code which works as I needed.

function weekCount(year, month_number) {
    var firstOfMonth = new Date(year, month_number-1, 1);
    var lastOfMonth = new Date(year, month_number, 0);
    var used = firstOfMonth.getDay() + lastOfMonth.getDate();
    return Math.ceil( used / 7);
 }
 Date.prototype.getWeekNumber = function(){
    var d = new Date(+this);
    d.setHours(0,0,0);
    d.setDate(d.getDate()+4-(d.getDay()||7));
    return Math.ceil((((d-new Date(d.getFullYear(),0,1))/8.64e7)+1)/7);
  };

  var year = parseInt($(this).text());
  var months = {1:'leden',2:'únor',3:'březen',4:'duben',5:'květen',6:'červen',7:'červenec',8:'srpen',9:'září',10:'říjen',11:'listopad',12:'prosinec'};
  var calendar = $('<div id="summary_search_form_menu"></div>');
  calendar.offset({top:$(this).offset().top + $(this).height() + 10}).css({right: '15px'});
  var cur_week = 0;
  var col1 = $('<div id="summary_search_form_menu_col1"></div>');
  var col2 = $('<div id="summary_search_form_menu_col2"></div>');
  calendar.append(col1);
  calendar.append(col2);
  var col2_table = $('<div id="summary_search_form_menu_col2_table"></div>');
  col2.append(col2_table);
  for (var i=1;i<=12;i++) {
    var row = $('<div class="row"></div>');
    col1.append('<div class="month button dark-blue">'+months[i]+'</div>');
    var week_count = weekCount(year, i);
    var d = new Date(year, i-1, 1, 0,0,0);
    var first_week_in_month = d.getWeekNumber();
    for (var week=(cur_week == first_week_in_month ? 2 : 1);week<=week_count;week++) {
      cur_week++;
      row.append('<div class="week button blue">'+cur_week+'</div>');
    }
    col2_table.append(row);
  }
  $('body').append(calendar);

How to get week numbers in month in Javascript?

1 Answers1