1 d3.time.week = function(date) {

     2   (date = d3.time.day(date)).setDate(date.getDate() - date.getDay());

     3   return date;

     4 };

     5 

     6 d3.time.week.utc = function(date) {

     7   (date = d3.time.day.utc(date)).setUTCDate(date.getUTCDate() - date.getUTCDay());

     8   return date;

     9 };