Limit minimum endsOn datetime selector to current beginsOn, set correct

date of first week and translate labels on datepicker

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

js/src/utils/datetime.ts

@@ -0,0 +1,21 @@
+function localeMonthNames(): string[] {
+  const monthNames: string[] = [];
+  for (let i = 0; i < 12; i += 1) {
+    const d = new Date(2019, i, 1);
+    const month = d.toLocaleString('default', { month: 'long' });
+    monthNames.push(month);
+  }
+  return monthNames;
+}
+
+function localeShortWeekDayNames(): string[] {
+  const weekDayNames: string[] = [];
+  for (let i = 13; i < 20; i += 1) {
+    const d = new Date(2019, 9, i);
+    const weekDay = d.toLocaleString('default', { weekday: 'short' });
+    weekDayNames.push(weekDay);
+  }
+  return weekDayNames;
+}
+
+export { localeMonthNames, localeShortWeekDayNames };