Date.prototype.getUTCWeekYear = function()

in src/retention.js [15:19]


Date.prototype.getUTCWeekYear = function() {
  var date = new Date(this.getTime());
  date.setUTCDate(date.getUTCDate() + 3 - (date.getUTCDay() + 6) % 7);
  return date.getUTCFullYear();
};