add front end code (#27)

web/src/utils/date.ts

@@ -0,0 +1,20 @@
+import moment from 'moment';
+
+export function today() {
+  return formatDate(moment());
+}
+
+export function lastDay() {
+  return formatDate(moment().subtract(1, 'days'));
+}
+
+export function lastWeek() {
+  return formatDate(moment().subtract(1, 'weeks'));
+}
+
+export function formatDate(date) {
+  if (!date) {
+    return '';
+  }
+  return moment(date).format('YYYY-MM-DD');
+}