heatmaps: part 2

website/src/heatmap/time.js

@@ -0,0 +1,31 @@
+const DAY_MS = 86_400_000;
+
+/**
+ * @param {Date} date
+ */
+export function toISODate(date) {
+  return date.toISOString().slice(0, 10);
+}
+
+export function todayISODate() {
+  return toISODate(new Date());
+}
+
+/**
+ * Inclusive UTC date range.
+ *
+ * @param {string} from
+ * @param {string} to
+ */
+export function dateRange(from, to) {
+  const dates = [];
+  for (
+    let time = Date.parse(`${from}T00:00:00Z`),
+      end = Date.parse(`${to}T00:00:00Z`);
+    time <= end;
+    time += DAY_MS
+  ) {
+    dates.push(toISODate(new Date(time)));
+  }
+  return dates;
+}