Bar graph added.

node_modules/d3-time/src/utcDay.js

@@ -0,0 +1,15 @@
+import interval from "./interval.js";
+import {durationDay} from "./duration.js";
+
+var utcDay = interval(function(date) {
+  date.setUTCHours(0, 0, 0, 0);
+}, function(date, step) {
+  date.setUTCDate(date.getUTCDate() + step);
+}, function(start, end) {
+  return (end - start) / durationDay;
+}, function(date) {
+  return date.getUTCDate() - 1;
+});
+
+export default utcDay;
+export var utcDays = utcDay.range;