Use `isSameDay` and `isToday` utilities

ts/components/conversation/TimelineItem.tsx

@@ -4,9 +4,9 @@
 import type { ReactChild, RefObject } from 'react';
 import React from 'react';
 import { omit } from 'lodash';
-import moment from 'moment';
 
 import type { LocalizerType, ThemeType } from '../../types/Util';
+import { isSameDay } from '../../util/timestamp';
 
 import type { InteractionModeType } from '../../state/ducks/conversations';
 import { TimelineDateHeader } from './TimelineDateHeader';
@@ -344,7 +344,7 @@ export class TimelineItem extends React.PureComponent<PropsType> {
         previousItem &&
           // This comparison avoids strange header behavior for out-of-order messages.
           item.timestamp > previousItem.timestamp &&
-          !moment(previousItem.timestamp).isSame(item.timestamp, 'day')
+          !isSameDay(previousItem.timestamp, item.timestamp)
       );
     if (shouldRenderDateHeader) {
       return (

ts/test-both/util/timestamp_test.ts

@@ -5,20 +5,21 @@ import { assert } from 'chai';
 import * as sinon from 'sinon';
 import moment from 'moment';
 import type { LocalizerType } from '../../types/Util';
+import { HOUR, DAY } from '../../util/durations';
 
 import {
-  isOlderThan,
-  isMoreRecentThan,
-  toDayMillis,
   formatDate,
   formatDateTimeLong,
   formatDateTimeShort,
   formatTime,
+  isMoreRecentThan,
+  isOlderThan,
+  isSameDay,
+  isToday,
+  toDayMillis,
 } from '../../util/timestamp';
 
 const FAKE_NOW = new Date('2020-01-23T04:56:00.000');
-const ONE_HOUR = 3600 * 1000;
-const ONE_DAY = 24 * ONE_HOUR;
 
 describe('timestamp', () => {
   function useFakeTimers() {
@@ -229,28 +230,68 @@ describe('timestamp', () => {
 
   describe('isOlderThan', () => {
     it('returns false on recent and future timestamps', () => {
-      assert.isFalse(isOlderThan(Date.now(), ONE_DAY));
-      assert.isFalse(isOlderThan(Date.now() + ONE_DAY, ONE_DAY));
+      assert.isFalse(isOlderThan(Date.now(), DAY));
+      assert.isFalse(isOlderThan(Date.now() + DAY, DAY));
     });
 
     it('returns true on old enough timestamps', () => {
-      assert.isFalse(isOlderThan(Date.now() - ONE_DAY + ONE_HOUR, ONE_DAY));
-      assert.isTrue(isOlderThan(Date.now() - ONE_DAY - ONE_HOUR, ONE_DAY));
+      assert.isFalse(isOlderThan(Date.now() - DAY + HOUR, DAY));
+      assert.isTrue(isOlderThan(Date.now() - DAY - HOUR, DAY));
     });
   });
 
   describe('isMoreRecentThan', () => {
     it('returns true on recent and future timestamps', () => {
-      assert.isTrue(isMoreRecentThan(Date.now(), ONE_DAY));
-      assert.isTrue(isMoreRecentThan(Date.now() + ONE_DAY, ONE_DAY));
+      assert.isTrue(isMoreRecentThan(Date.now(), DAY));
+      assert.isTrue(isMoreRecentThan(Date.now() + DAY, DAY));
     });
 
     it('returns false on old enough timestamps', () => {
-      assert.isTrue(isMoreRecentThan(Date.now() - ONE_DAY + ONE_HOUR, ONE_DAY));
+      assert.isTrue(isMoreRecentThan(Date.now() - DAY + HOUR, DAY));
+      assert.isFalse(isMoreRecentThan(Date.now() - DAY - HOUR, DAY));
+    });
+  });
+
+  describe('isSameDay', () => {
+    it('returns false for different days', () => {
       assert.isFalse(
-        isMoreRecentThan(Date.now() - ONE_DAY - ONE_HOUR, ONE_DAY)
+        isSameDay(
+          new Date(1998, 10, 21, 12, 34, 56, 123),
+          new Date(2006, 10, 21, 12, 34, 56, 123)
+        )
       );
     });
+
+    it('returns true for identical timestamps', () => {
+      const timestamp = new Date(1998, 10, 21, 12, 34, 56, 123);
+      assert.isTrue(isSameDay(timestamp, timestamp));
+    });
+
+    it('returns true for times on the same day', () => {
+      assert.isTrue(
+        isSameDay(
+          new Date(1998, 10, 21, 12, 34, 56, 123),
+          new Date(1998, 10, 21, 1, 23, 45, 123)
+        )
+      );
+    });
+  });
+
+  describe('isToday', () => {
+    useFakeTimers();
+
+    it('returns false for days other than today', () => {
+      assert.isFalse(isToday(Date.now() + DAY));
+      assert.isFalse(isToday(Date.now() - DAY));
+    });
+
+    it('returns true right now', () => {
+      assert.isTrue(isToday(Date.now()));
+    });
+
+    it('returns true for times today', () => {
+      assert.isTrue(isToday(new Date('2020-01-23T03:56:00.000')));
+    });
   });
 
   describe('toDayMillis', () => {

ts/util/getMutedUntilText.ts

@@ -1,8 +1,9 @@
-// Copyright 2021 Signal Messenger, LLC
+// Copyright 2021-2022 Signal Messenger, LLC
 // SPDX-License-Identifier: AGPL-3.0-only
 
 import moment from 'moment';
 import type { LocalizerType } from '../types/Util';
+import { isToday } from './timestamp';
 
 /**
  * Returns something like "Muted until 6:09 PM", localized.
@@ -18,7 +19,7 @@ export function getMutedUntilText(
   }
 
   const expires = moment(muteExpiresAt);
-  const muteExpirationUntil = moment().isSame(expires, 'day')
+  const muteExpirationUntil = isToday(expires)
     ? expires.format('LT')
     : expires.format('L, LT');
 

ts/util/timestamp.ts

@@ -31,10 +31,10 @@ export function toDayMillis(timestamp: number): number {
   return timestamp - (timestamp % DAY);
 }
 
-const isSameDay = (a: RawTimestamp, b: RawTimestamp): boolean =>
+export const isSameDay = (a: RawTimestamp, b: RawTimestamp): boolean =>
   moment(a).isSame(b, 'day');
 
-const isToday = (rawTimestamp: RawTimestamp): boolean =>
+export const isToday = (rawTimestamp: RawTimestamp): boolean =>
   isSameDay(rawTimestamp, Date.now());
 
 const isYesterday = (rawTimestamp: RawTimestamp): boolean =>