Function ceil

d3-3.2.8/d3.js:8225–8228

(date)

      return date - d0 < d1 - date ? d0 : d1;
    }
    function ceil(date) {
      step(date = local(new d3_time(date - 1)), 1);
      return date;
    }
    function offset(date, k) {
      step(date = new d3_time(+date), k);
      return date;