used Intl for daylight savings

Author: glickgNU

src/frontend/src/pages/CalendarPage/Components/ScheduleEventModal.tsx

@@ -13,7 +13,7 @@ import { useToast } from '../../../hooks/toasts.hooks';
 import { formatEventTime } from 'shared';
 import { datePipe } from '../../../utils/pipes';
 import { routes } from '../../../utils/routes';
-import { formatHourInCurrentTimeZone, offsetDate } from '../../../utils/design-review.utils';
+import { offsetDate } from '../../../utils/design-review.utils';
 
 interface ScheduleEventModalProps {
   open: boolean;
@@ -79,8 +79,7 @@ const ScheduleEventModal: React.FC<ScheduleEventModalProps> = ({
           >
             <Typography variant="h6">{datePipe(offsetDate(dateToShow()))}</Typography>
             <Typography variant="body1" color="text.secondary">
-              {formatHourInCurrentTimeZone(formatEventTime(startTime))} -
-              {formatHourInCurrentTimeZone(formatEventTime(endTime))}
+              {formatEventTime(startTime)} -{formatEventTime(endTime)}
             </Typography>
           </Box>
 

src/frontend/src/pages/CalendarPage/EventPartialInfoView.tsx

@@ -7,7 +7,6 @@ import { getTeamTypeIcon } from './CalendarDayCard';
 import { Typography } from '@mui/material';
 
 import { getMutedColor } from '../../utils/calendar.utils';
-import { formatHourInCurrentTimeZone } from '../../utils/design-review.utils';
 
 interface EventInfoProps {
   event: EventInstance;
@@ -78,8 +77,7 @@ const EventPartialInfoView: React.FC<EventInfoProps> = ({ event, eventTypes, cal
             </Typography>
           ) : (
             <Typography marginX={0.5} marginY={0.5} lineHeight={'120%'} fontSize={12} fontWeight="bold" align="left">
-              {formatHourInCurrentTimeZone(formatEventTime(event.startTime))} -{' '}
-              {formatHourInCurrentTimeZone(formatEventTime(event.endTime))}
+              {formatEventTime(event.startTime)} - {formatEventTime(event.endTime)}
             </Typography>
           )}
         </Stack>

src/frontend/src/utils/design-review.utils.ts

@@ -54,24 +54,21 @@ export const HeatmapColors = ['#D9D9D9', '#C1E0C1', '#9BE89B', '#7AE47A', '#45EF
 
 export const NUMBER_OF_TIME_SLOTS = enumToArray(REVIEW_TIMES).length * enumToArray(DAY_NAMES).length;
 
-const nthWeekday = (year: number, month: MONTH_NAMES, weekday: DAY_NAMES, nth: number) => {
-  const day = new Date(year, month!, 1);
-  const dayDiff = (weekday! - day.getDay() + 7) % 7;
+const ESTOffset = () => {
+  const parts = new Intl.DateTimeFormat('en', {
+    timeZone: 'America/New_York',
+    timeZoneName: 'shortOffset'
+  }).formatToParts(new Date());
 
-  return new Date(year, month, 1 + dayDiff + (nth - 1) * 7);
-};
-
-const daylightSavings = () => {
-  const currDate = new Date();
+  const GMTTime = parts.find((t) => t.type === 'timeZoneName');
+  const offsetEST = Number(GMTTime!.value.replace('GMT', ''));
 
-  const start = nthWeekday(currDate.getFullYear(), MONTH_NAMES.March, DAY_NAMES.Sunday, 2);
-  const end = nthWeekday(currDate.getFullYear(), MONTH_NAMES.November, DAY_NAMES.Sunday, 1);
-  return currDate >= start && currDate < end;
+  return offsetEST;
 };
 
 export const userOffsetTime = () => {
   const UTCOffset = -new Date().getTimezoneOffset() / 60;
-  const EST = daylightSavings() ? -4 : -5;
+  const EST = ESTOffset();
   const userOffset = UTCOffset - EST;
   return userOffset;
 };