Use Intl to localise dates and times (#11422)

* Use Intl to generate better internationalised date formats

* Get `Yesterday` and `Today` from Intl also

* Correct capitalisation blunder

* Fix formatTime include weekday

* Iterate

* Fix tests

* use jest setSystemTime

* Discard changes to cypress/e2e/settings/general-user-settings-tab.spec.ts

* Discard changes to res/css/_components.pcss

* Discard changes to res/css/views/elements/_LanguageDropdown.pcss

* Discard changes to src/components/views/elements/LanguageDropdown.tsx

* Add docs & tests for getDaysArray & getMonthsArray

* Discard changes to test/components/structures/__snapshots__/MatrixChat-test.tsx.snap

* Consolidate consts

* Improve testing & documentation

* Update snapshot

* Apply suggestions from code review

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>

* Iterate

* Clarify comments

* Update src/DateUtils.ts

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>

* Specify hourCycle

* Discard changes to test/components/views/settings/devices/DeviceDetails-test.tsx

* Update comments

---------

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>

cypress/e2e/editing/editing.spec.ts

@@ -119,7 +119,7 @@ describe("Editing", () => {
                 // Assert that the date separator is rendered at the top
                 cy.get("li:nth-child(1) .mx_DateSeparator").within(() => {
                     cy.get("h2").within(() => {
-                        cy.findByText("Today");
+                        cy.findByText("today").should("have.css", "text-transform", "capitalize");
                     });
                 });
 
@@ -184,7 +184,7 @@ describe("Editing", () => {
                 // Assert that the date is rendered
                 cy.get("li:nth-child(1) .mx_DateSeparator").within(() => {
                     cy.get("h2").within(() => {
-                        cy.findByText("Today");
+                        cy.findByText("today").should("have.css", "text-transform", "capitalize");
                     });
                 });
 

res/css/views/messages/_DateSeparator.pcss

@@ -40,6 +40,7 @@ limitations under the License.
     font-size: inherit;
     font-weight: inherit;
     color: inherit;
+    text-transform: capitalize;
 }
 
 .mx_DateSeparator_jumpToDateMenu {

src/DateUtils.ts

@@ -18,95 +18,121 @@ limitations under the License.
 
 import { Optional } from "matrix-events-sdk";
 
-import { _t } from "./languageHandler";
+import { _t, getUserLanguage } from "./languageHandler";
 
-function getDaysArray(): string[] {
+export const MINUTE_MS = 60000;
-    return [_t("Sun"), _t("Mon"), _t("Tue"), _t("Wed"), _t("Thu"), _t("Fri"), _t("Sat")];
+export const HOUR_MS = MINUTE_MS * 60;
+export const DAY_MS = HOUR_MS * 24;
+
+/**
+ * Returns array of 7 weekday names, from Sunday to Saturday, internationalised to the user's language.
+ * @param weekday - format desired "short" | "long" | "narrow"
+ */
+export function getDaysArray(weekday: Intl.DateTimeFormatOptions["weekday"] = "short"): string[] {
+    const sunday = 1672574400000; // 2023-01-01 12:00 UTC
+    const { format } = new Intl.DateTimeFormat(getUserLanguage(), { weekday, timeZone: "UTC" });
+    return [...Array(7).keys()].map((day) => format(sunday + day * DAY_MS));
 }
 
-function getMonthsArray(): string[] {
+/**
-    return [
+ * Returns array of 12 month names, from January to December, internationalised to the user's language.
-        _t("Jan"),
+ * @param month - format desired "numeric" | "2-digit" | "long" | "short" | "narrow"
-        _t("Feb"),
+ */
-        _t("Mar"),
+export function getMonthsArray(month: Intl.DateTimeFormatOptions["month"] = "short"): string[] {
-        _t("Apr"),
+    const { format } = new Intl.DateTimeFormat(getUserLanguage(), { month, timeZone: "UTC" });
-        _t("May"),
+    return [...Array(12).keys()].map((m) => format(Date.UTC(2021, m)));
-        _t("Jun"),
-        _t("Jul"),
-        _t("Aug"),
-        _t("Sep"),
-        _t("Oct"),
-        _t("Nov"),
-        _t("Dec"),
-    ];
 }
 
-function pad(n: number): string {
+// XXX: Ideally we could just specify `hour12: boolean` but it has issues on Chrome in the `en` locale
-    return (n < 10 ? "0" : "") + n;
+// https://support.google.com/chrome/thread/29828561?hl=en
+function getTwelveHourOptions(showTwelveHour: boolean): Intl.DateTimeFormatOptions {
+    return {
+        hourCycle: showTwelveHour ? "h12" : "h23",
+    };
 }
 
-function twelveHourTime(date: Date, showSeconds = false): string {
+/**
-    let hours = date.getHours() % 12;
+ * Formats a given date to a date & time string.
-    const minutes = pad(date.getMinutes());
+ *
-    const ampm = date.getHours() >= 12 ? _t("PM") : _t("AM");
+ * The output format depends on how far away the given date is from now.
-    hours = hours ? hours : 12; // convert 0 -> 12
+ * Will use the browser's default time zone.
-    if (showSeconds) {
+ * If the date is today it will return a time string excluding seconds. See {@formatTime}.
-        const seconds = pad(date.getSeconds());
+ * If the date is within the last 6 days it will return the name of the weekday along with the time string excluding seconds.
-        return `${hours}:${minutes}:${seconds}${ampm}`;
+ * If the date is within the same year then it will return the weekday, month and day of the month along with the time string excluding seconds.
-    }
+ * Otherwise, it will return a string representing the full date & time in a human friendly manner. See {@formatFullDate}.
-    return `${hours}:${minutes}${ampm}`;
+ * @param date - date object to format
-}
+ * @param showTwelveHour - whether to use 12-hour rather than 24-hour time. Defaults to `false` (24 hour mode).
-
+ *        Overrides the default from the locale, whether `true` or `false`.
-export function formatDate(date: Date, showTwelveHour = false): string {
+ * @param locale - the locale string to use, in BCP 47 format, defaulting to user's selected application locale
+ */
+export function formatDate(date: Date, showTwelveHour = false, locale?: string): string {
+    const _locale = locale ?? getUserLanguage();
     const now = new Date();
-    const days = getDaysArray();
-    const months = getMonthsArray();
     if (date.toDateString() === now.toDateString()) {
-        return formatTime(date, showTwelveHour);
+        return formatTime(date, showTwelveHour, _locale);
-    } else if (now.getTime() - date.getTime() < 6 * 24 * 60 * 60 * 1000) {
+    } else if (now.getTime() - date.getTime() < 6 * DAY_MS) {
-        // TODO: use standard date localize function provided in counterpart
+        // Time is within the last 6 days (or in the future)
-        return _t("%(weekDayName)s %(time)s", {
+        return new Intl.DateTimeFormat(_locale, {
-            weekDayName: days[date.getDay()],
+            ...getTwelveHourOptions(showTwelveHour),
-            time: formatTime(date, showTwelveHour),
+            weekday: "short",
-        });
+            hour: "numeric",
+            minute: "2-digit",
+        }).format(date);
     } else if (now.getFullYear() === date.getFullYear()) {
-        // TODO: use standard date localize function provided in counterpart
+        return new Intl.DateTimeFormat(_locale, {
-        return _t("%(weekDayName)s, %(monthName)s %(day)s %(time)s", {
+            ...getTwelveHourOptions(showTwelveHour),
-            weekDayName: days[date.getDay()],
+            weekday: "short",
-            monthName: months[date.getMonth()],
+            month: "short",
-            day: date.getDate(),
+            day: "numeric",
-            time: formatTime(date, showTwelveHour),
+            hour: "numeric",
-        });
+            minute: "2-digit",
+        }).format(date);
     }
-    return formatFullDate(date, showTwelveHour);
+    return formatFullDate(date, showTwelveHour, false, _locale);
 }
 
-export function formatFullDateNoTime(date: Date): string {
+/**
-    const days = getDaysArray();
+ * Formats a given date to a human-friendly string with short weekday.
-    const months = getMonthsArray();
+ * Will use the browser's default time zone.
-    return _t("%(weekDayName)s, %(monthName)s %(day)s %(fullYear)s", {
+ * @example "Thu, 17 Nov 2022" in en-GB locale
-        weekDayName: days[date.getDay()],
+ * @param date - date object to format
-        monthName: months[date.getMonth()],
+ * @param locale - the locale string to use, in BCP 47 format, defaulting to user's selected application locale
-        day: date.getDate(),
+ */
-        fullYear: date.getFullYear(),
+export function formatFullDateNoTime(date: Date, locale?: string): string {
-    });
+    return new Intl.DateTimeFormat(locale ?? getUserLanguage(), {
+        weekday: "short",
+        month: "short",
+        day: "numeric",
+        year: "numeric",
+    }).format(date);
 }
 
-export function formatFullDate(date: Date, showTwelveHour = false, showSeconds = true): string {
+/**
-    const days = getDaysArray();
+ * Formats a given date to a date & time string, optionally including seconds.
-    const months = getMonthsArray();
+ * Will use the browser's default time zone.
-    return _t("%(weekDayName)s, %(monthName)s %(day)s %(fullYear)s %(time)s", {
+ * @example "Thu, 17 Nov 2022, 4:58:32 pm" in en-GB locale with showTwelveHour=true and showSeconds=true
-        weekDayName: days[date.getDay()],
+ * @param date - date object to format
-        monthName: months[date.getMonth()],
+ * @param showTwelveHour - whether to use 12-hour rather than 24-hour time. Defaults to `false` (24 hour mode).
-        day: date.getDate(),
+ *        Overrides the default from the locale, whether `true` or `false`.
-        fullYear: date.getFullYear(),
+ * @param showSeconds - whether to include seconds in the time portion of the string
-        time: showSeconds ? formatFullTime(date, showTwelveHour) : formatTime(date, showTwelveHour),
+ * @param locale - the locale string to use, in BCP 47 format, defaulting to user's selected application locale
-    });
+ */
+export function formatFullDate(date: Date, showTwelveHour = false, showSeconds = true, locale?: string): string {
+    return new Intl.DateTimeFormat(locale ?? getUserLanguage(), {
+        ...getTwelveHourOptions(showTwelveHour),
+        weekday: "short",
+        month: "short",
+        day: "numeric",
+        year: "numeric",
+        hour: "numeric",
+        minute: "2-digit",
+        second: showSeconds ? "2-digit" : undefined,
+    }).format(date);
 }
 
 /**
  * Formats dates to be compatible with attributes of a `<input type="date">`. Dates
- * should be formatted like "2020-06-23" (formatted according to ISO8601)
+ * should be formatted like "2020-06-23" (formatted according to ISO8601).
  *
  * @param date The date to format.
  * @returns The date string in ISO8601 format ready to be used with an `<input>`
@@ -115,22 +141,44 @@ export function formatDateForInput(date: Date): string {
     const year = `${date.getFullYear()}`.padStart(4, "0");
     const month = `${date.getMonth() + 1}`.padStart(2, "0");
     const day = `${date.getDate()}`.padStart(2, "0");
-    const dateInputValue = `${year}-${month}-${day}`;
+    return `${year}-${month}-${day}`;
-    return dateInputValue;
 }
 
-export function formatFullTime(date: Date, showTwelveHour = false): string {
+/**
-    if (showTwelveHour) {
+ * Formats a given date to a time string including seconds.
-        return twelveHourTime(date, true);
+ * Will use the browser's default time zone.
-    }
+ * @example "4:58:32 PM" in en-GB locale with showTwelveHour=true
-    return pad(date.getHours()) + ":" + pad(date.getMinutes()) + ":" + pad(date.getSeconds());
+ * @example "16:58:32" in en-GB locale with showTwelveHour=false
+ * @param date - date object to format
+ * @param showTwelveHour - whether to use 12-hour rather than 24-hour time. Defaults to `false` (24 hour mode).
+ *        Overrides the default from the locale, whether `true` or `false`.
+ * @param locale - the locale string to use, in BCP 47 format, defaulting to user's selected application locale
+ */
+export function formatFullTime(date: Date, showTwelveHour = false, locale?: string): string {
+    return new Intl.DateTimeFormat(locale ?? getUserLanguage(), {
+        ...getTwelveHourOptions(showTwelveHour),
+        hour: "numeric",
+        minute: "2-digit",
+        second: "2-digit",
+    }).format(date);
 }
 
-export function formatTime(date: Date, showTwelveHour = false): string {
+/**
-    if (showTwelveHour) {
+ * Formats a given date to a time string excluding seconds.
-        return twelveHourTime(date);
+ * Will use the browser's default time zone.
-    }
+ * @example "4:58 PM" in en-GB locale with showTwelveHour=true
-    return pad(date.getHours()) + ":" + pad(date.getMinutes());
+ * @example "16:58" in en-GB locale with showTwelveHour=false
+ * @param date - date object to format
+ * @param showTwelveHour - whether to use 12-hour rather than 24-hour time. Defaults to `false` (24 hour mode).
+ *        Overrides the default from the locale, whether `true` or `false`.
+ * @param locale - the locale string to use, in BCP 47 format, defaulting to user's selected application locale
+ */
+export function formatTime(date: Date, showTwelveHour = false, locale?: string): string {
+    return new Intl.DateTimeFormat(locale ?? getUserLanguage(), {
+        ...getTwelveHourOptions(showTwelveHour),
+        hour: "numeric",
+        minute: "2-digit",
+    }).format(date);
 }
 
 export function formatSeconds(inSeconds: number): string {
@@ -183,9 +231,8 @@ export function formatTimeLeft(inSeconds: number): string {
     });
 }
 
-const MILLIS_IN_DAY = 86400000;
 function withinPast24Hours(prevDate: Date, nextDate: Date): boolean {
-    return Math.abs(prevDate.getTime() - nextDate.getTime()) <= MILLIS_IN_DAY;
+    return Math.abs(prevDate.getTime() - nextDate.getTime()) <= DAY_MS;
 }
 
 function withinCurrentDay(prevDate: Date, nextDate: Date): boolean {
@@ -210,15 +257,15 @@ export function wantsDateSeparator(prevEventDate: Optional<Date>, nextEventDate:
 }
 
 export function formatFullDateNoDay(date: Date): string {
+    const locale = getUserLanguage();
     return _t("%(date)s at %(time)s", {
-        date: date.toLocaleDateString().replace(/\//g, "-"),
+        date: date.toLocaleDateString(locale).replace(/\//g, "-"),
-        time: date.toLocaleTimeString().replace(/:/g, "-"),
+        time: date.toLocaleTimeString(locale).replace(/:/g, "-"),
     });
 }
 
 /**
- * Returns an ISO date string without textual description of the date (ie: no "Wednesday" or
+ * Returns an ISO date string without textual description of the date (ie: no "Wednesday" or similar)
- * similar)
  * @param date The date to format.
  * @returns The date string in ISO format.
  */
@@ -226,12 +273,23 @@ export function formatFullDateNoDayISO(date: Date): string {
     return date.toISOString();
 }
 
-export function formatFullDateNoDayNoTime(date: Date): string {
+/**
-    return date.getFullYear() + "/" + pad(date.getMonth() + 1) + "/" + pad(date.getDate());
+ * Formats a given date to a string.
+ * Will use the browser's default time zone.
+ * @example 17/11/2022 in en-GB locale
+ * @param date - date object to format
+ * @param locale - the locale string to use, in BCP 47 format, defaulting to user's selected application locale
+ */
+export function formatFullDateNoDayNoTime(date: Date, locale?: string): string {
+    return new Intl.DateTimeFormat(locale ?? getUserLanguage(), {
+        year: "numeric",
+        month: "numeric",
+        day: "numeric",
+    }).format(date);
 }
 
 export function formatRelativeTime(date: Date, showTwelveHour = false): string {
-    const now = new Date(Date.now());
+    const now = new Date();
     if (withinCurrentDay(date, now)) {
         return formatTime(date, showTwelveHour);
     } else {
@@ -245,15 +303,11 @@ export function formatRelativeTime(date: Date, showTwelveHour = false): string {
     }
 }
 
-const MINUTE_MS = 60000;
-const HOUR_MS = MINUTE_MS * 60;
-const DAY_MS = HOUR_MS * 24;
-
 /**
- * Formats duration in ms to human readable string
+ * Formats duration in ms to human-readable string
- * Returns value in biggest possible unit (day, hour, min, second)
+ * Returns value in the biggest possible unit (day, hour, min, second)
  * Rounds values up until unit threshold
- * ie. 23:13:57 -> 23h, 24:13:57 -> 1d, 44:56:56 -> 2d
+ * i.e. 23:13:57 -> 23h, 24:13:57 -> 1d, 44:56:56 -> 2d
  */
 export function formatDuration(durationMs: number): string {
     if (durationMs >= DAY_MS) {
@@ -269,9 +323,9 @@ export function formatDuration(durationMs: number): string {
 }
 
 /**
- * Formats duration in ms to human readable string
+ * Formats duration in ms to human-readable string
  * Returns precise value down to the nearest second
- * ie. 23:13:57 -> 23h 13m 57s, 44:56:56 -> 1d 20h 56m 56s
+ * i.e. 23:13:57 -> 23h 13m 57s, 44:56:56 -> 1d 20h 56m 56s
  */
 export function formatPreciseDuration(durationMs: number): string {
     const days = Math.floor(durationMs / DAY_MS);
@@ -293,13 +347,13 @@ export function formatPreciseDuration(durationMs: number): string {
 
 /**
  * Formats a timestamp to a short date
- * (eg 25/12/22 in uk locale)
+ * Similar to {@formatFullDateNoDayNoTime} but with 2-digit on day, month, year.
- * localised by system locale
+ * @example 25/12/22 in en-GB locale
  * @param timestamp - epoch timestamp
+ * @param locale - the locale string to use, in BCP 47 format, defaulting to user's selected application locale
  * @returns {string} formattedDate
  */
-export const formatLocalDateShort = (timestamp: number): string =>
+export const formatLocalDateShort = (timestamp: number, locale?: string): string =>
-    new Intl.DateTimeFormat(
+    new Intl.DateTimeFormat(locale ?? getUserLanguage(), { day: "2-digit", month: "2-digit", year: "2-digit" }).format(
-        undefined, // locales
+        timestamp,
-        { day: "2-digit", month: "2-digit", year: "2-digit" },
+    );
-    ).format(timestamp);

src/components/views/dialogs/ForwardDialog.tsx

@@ -216,6 +216,7 @@ const ForwardDialog: React.FC<IProps> = ({ matrixClient: cli, event, permalinkCr
         },
         event_id: "$9999999999999999999999999999999999999999999",
         room_id: event.getRoomId(),
+        origin_server_ts: event.getTs(),
     });
     mockEvent.sender = {
         name: profileInfo.displayname || userId,

src/components/views/messages/DateSeparator.tsx

@@ -19,8 +19,8 @@ import React from "react";
 import { Direction, ConnectionError, MatrixError, HTTPError } from "matrix-js-sdk/src/matrix";
 import { logger } from "matrix-js-sdk/src/logger";
 
-import { _t } from "../../../languageHandler";
+import { _t, getUserLanguage } from "../../../languageHandler";
-import { formatFullDateNoDay, formatFullDateNoTime } from "../../../DateUtils";
+import { formatFullDateNoDay, formatFullDateNoTime, getDaysArray } from "../../../DateUtils";
 import { MatrixClientPeg } from "../../../MatrixClientPeg";
 import dispatcher from "../../../dispatcher/dispatcher";
 import { Action } from "../../../dispatcher/actions";
@@ -40,10 +40,6 @@ import JumpToDatePicker from "./JumpToDatePicker";
 import { ViewRoomPayload } from "../../../dispatcher/payloads/ViewRoomPayload";
 import { SdkContextClass } from "../../../contexts/SDKContext";
 
-function getDaysArray(): string[] {
-    return [_t("Sunday"), _t("Monday"), _t("Tuesday"), _t("Wednesday"), _t("Thursday"), _t("Friday"), _t("Saturday")];
-}
-
 interface IProps {
     roomId: string;
     ts: number;
@@ -105,15 +101,16 @@ export default class DateSeparator extends React.Component<IProps, IState> {
 
         const today = new Date();
         const yesterday = new Date();
-        const days = getDaysArray();
+        const days = getDaysArray("long");
         yesterday.setDate(today.getDate() - 1);
 
+        const relativeTimeFormat = new Intl.RelativeTimeFormat(getUserLanguage(), { style: "long", numeric: "auto" });
         if (date.toDateString() === today.toDateString()) {
-            return _t("Today");
+            return relativeTimeFormat.format(0, "day"); // Today
         } else if (date.toDateString() === yesterday.toDateString()) {
-            return _t("Yesterday");
+            return relativeTimeFormat.format(-1, "day"); // Yesterday
         } else if (today.getTime() - date.getTime() < 6 * 24 * 60 * 60 * 1000) {
-            return days[date.getDay()];
+            return days[date.getDay()]; // Sunday-Saturday
         } else {
             return formatFullDateNoTime(date);
         }

src/i18n/strings/en_EN.json

@@ -27,31 +27,6 @@
     "Server may be unavailable, overloaded, or you hit a bug.": "Server may be unavailable, overloaded, or you hit a bug.",
     "The server does not support the room version specified.": "The server does not support the room version specified.",
     "Failure to create room": "Failure to create room",
-    "Sun": "Sun",
-    "Mon": "Mon",
-    "Tue": "Tue",
-    "Wed": "Wed",
-    "Thu": "Thu",
-    "Fri": "Fri",
-    "Sat": "Sat",
-    "Jan": "Jan",
-    "Feb": "Feb",
-    "Mar": "Mar",
-    "Apr": "Apr",
-    "May": "May",
-    "Jun": "Jun",
-    "Jul": "Jul",
-    "Aug": "Aug",
-    "Sep": "Sep",
-    "Oct": "Oct",
-    "Nov": "Nov",
-    "Dec": "Dec",
-    "PM": "PM",
-    "AM": "AM",
-    "%(weekDayName)s %(time)s": "%(weekDayName)s %(time)s",
-    "%(weekDayName)s, %(monthName)s %(day)s %(time)s": "%(weekDayName)s, %(monthName)s %(day)s %(time)s",
-    "%(weekDayName)s, %(monthName)s %(day)s %(fullYear)s": "%(weekDayName)s, %(monthName)s %(day)s %(fullYear)s",
-    "%(weekDayName)s, %(monthName)s %(day)s %(fullYear)s %(time)s": "%(weekDayName)s, %(monthName)s %(day)s %(fullYear)s %(time)s",
     "%(hours)sh %(minutes)sm %(seconds)ss left": "%(hours)sh %(minutes)sm %(seconds)ss left",
     "%(minutes)sm %(seconds)ss left": "%(minutes)sm %(seconds)ss left",
     "%(seconds)ss left": "%(seconds)ss left",
@@ -2401,15 +2376,6 @@
     },
     "%(name)s started a video call": "%(name)s started a video call",
     "Video call ended": "Video call ended",
-    "Sunday": "Sunday",
-    "Monday": "Monday",
-    "Tuesday": "Tuesday",
-    "Wednesday": "Wednesday",
-    "Thursday": "Thursday",
-    "Friday": "Friday",
-    "Saturday": "Saturday",
-    "Today": "Today",
-    "Yesterday": "Yesterday",
     "A network error occurred while trying to find and jump to the given date. Your homeserver might be down or there was just a temporary problem with your internet connection. Please try again. If this continues, please contact your homeserver administrator.": "A network error occurred while trying to find and jump to the given date. Your homeserver might be down or there was just a temporary problem with your internet connection. Please try again. If this continues, please contact your homeserver administrator.",
     "We were unable to find an event looking forwards from %(dateString)s. Try choosing an earlier date.": "We were unable to find an event looking forwards from %(dateString)s. Try choosing an earlier date.",
     "Server returned %(statusCode)s with error code %(errorCode)s": "Server returned %(statusCode)s with error code %(errorCode)s",

src/languageHandler.tsx

@@ -93,7 +93,7 @@ export class UserFriendlyError extends Error {
 
 export function getUserLanguage(): string {
     const language = SettingsStore.getValue("language", null, /*excludeDefault:*/ true);
-    if (language) {
+    if (typeof language === "string" && language !== "") {
         return language;
     } else {
         return normalizeLanguageKey(getLanguageFromBrowser());

test/components/structures/TimelinePanel-test.tsx

@@ -96,6 +96,7 @@ const mockEvents = (room: Room, count = 2): MatrixEvent[] => {
                 type: EventType.RoomMessage,
                 sender: "userId",
                 content: createMessageEventContent("`Event${index}`"),
+                origin_server_ts: index,
             }),
         );
     }
@@ -447,7 +448,7 @@ describe("TimelinePanel", () => {
 
             render(<TimelinePanel {...props} />);
 
-            const event = new MatrixEvent({ type: RoomEvent.Timeline });
+            const event = new MatrixEvent({ type: RoomEvent.Timeline, origin_server_ts: 0 });
             const data = { timeline: otherTimeline, liveEvent: true };
             client.emit(RoomEvent.Timeline, event, room, false, false, data);
 
@@ -463,7 +464,7 @@ describe("TimelinePanel", () => {
 
             render(<TimelinePanel {...props} />);
 
-            const event = new MatrixEvent({ type: RoomEvent.Timeline });
+            const event = new MatrixEvent({ type: RoomEvent.Timeline, origin_server_ts: 0 });
             const data = { timeline: props.timelineSet.getLiveTimeline(), liveEvent: false };
             client.emit(RoomEvent.Timeline, event, room, false, false, data);
 
@@ -479,7 +480,7 @@ describe("TimelinePanel", () => {
 
             render(<TimelinePanel {...props} />);
 
-            const event = new MatrixEvent({ type: RoomEvent.Timeline });
+            const event = new MatrixEvent({ type: RoomEvent.Timeline, origin_server_ts: 0 });
             const data = { timeline: props.timelineSet.getLiveTimeline(), liveEvent: false };
             const toStartOfTimeline = true;
             client.emit(RoomEvent.Timeline, event, room, toStartOfTimeline, false, data);
@@ -496,7 +497,7 @@ describe("TimelinePanel", () => {
 
             render(<TimelinePanel {...props} />);
 
-            const event = new MatrixEvent({ type: RoomEvent.Timeline });
+            const event = new MatrixEvent({ type: RoomEvent.Timeline, origin_server_ts: 0 });
             const data = { timeline: props.timelineSet.getLiveTimeline(), liveEvent: true };
             client.emit(RoomEvent.Timeline, event, room, false, false, data);
 
@@ -521,7 +522,7 @@ describe("TimelinePanel", () => {
 
             await flushPromises();
 
-            const event = new MatrixEvent({ type: RoomEvent.Timeline });
+            const event = new MatrixEvent({ type: RoomEvent.Timeline, origin_server_ts: 0 });
             const data = { timeline: props.timelineSet.getLiveTimeline(), liveEvent: true };
             client.emit(RoomEvent.Timeline, event, room, false, false, data);
 
@@ -539,11 +540,13 @@ describe("TimelinePanel", () => {
                 type: "m.call.invite",
                 room_id: virtualRoom.roomId,
                 event_id: `virtualCallEvent1`,
+                origin_server_ts: 0,
             });
             const virtualCallMetaEvent = new MatrixEvent({
                 type: "org.matrix.call.sdp_stream_metadata_changed",
                 room_id: virtualRoom.roomId,
                 event_id: `virtualCallEvent2`,
+                origin_server_ts: 0,
             });
             const virtualEvents = [virtualCallInvite, ...mockEvents(virtualRoom), virtualCallMetaEvent];
             const { timelineSet: overlayTimelineSet } = getProps(virtualRoom, virtualEvents);
@@ -819,6 +822,7 @@ describe("TimelinePanel", () => {
                 type: EventType.RoomMessage,
                 sender: "userId",
                 content: createMessageEventContent("ReplyEvent1"),
+                origin_server_ts: 0,
             });
 
             reply2 = new MatrixEvent({
@@ -827,6 +831,7 @@ describe("TimelinePanel", () => {
                 type: EventType.RoomMessage,
                 sender: "userId",
                 content: createMessageEventContent("ReplyEvent2"),
+                origin_server_ts: 0,
             });
 
             root = new MatrixEvent({
@@ -835,6 +840,7 @@ describe("TimelinePanel", () => {
                 type: EventType.RoomMessage,
                 sender: "userId",
                 content: createMessageEventContent("RootEvent"),
+                origin_server_ts: 0,
             });
 
             const eventMap: { [key: string]: MatrixEvent } = {

test/components/structures/__snapshots__/MessagePanel-test.tsx.snap

@@ -39,7 +39,7 @@ exports[`MessagePanel should handle lots of membership events quickly 1`] = `
           data-testid="__testid__"
         >
           <div
-            aria-label="Thu, Jan 1 1970"
+            aria-label="Thu, Jan 1, 1970"
             class="mx_DateSeparator"
             role="separator"
           >
@@ -53,7 +53,7 @@ exports[`MessagePanel should handle lots of membership events quickly 1`] = `
                 aria-hidden="true"
                 class="mx_DateSeparator_dateHeading"
               >
-                Thu, Jan 1 1970
+                Thu, Jan 1, 1970
               </h2>
             </div>
             <hr

test/components/views/dialogs/MessageEditHistoryDialog-test.tsx

@@ -51,7 +51,7 @@ describe("<MessageEditHistory />", () => {
                         new MatrixEvent({
                             type: EventType.RoomMessage,
                             room_id: roomId,
-                            origin_server_ts: e.ts,
+                            origin_server_ts: e.ts ?? 0,
                             content: {
                                 body: e.msg,
                             },

test/components/views/dialogs/__snapshots__/MessageEditHistoryDialog-test.tsx.snap

@@ -45,7 +45,7 @@ exports[`<MessageEditHistory /> should match the snapshot 1`] = `
           >
             <li>
               <div
-                aria-label="Thu, Jan 1 1970"
+                aria-label="Thu, Jan 1, 1970"
                 class="mx_DateSeparator"
                 role="separator"
               >
@@ -59,7 +59,7 @@ exports[`<MessageEditHistory /> should match the snapshot 1`] = `
                     aria-hidden="true"
                     class="mx_DateSeparator_dateHeading"
                   >
-                    Thu, Jan 1 1970
+                    Thu, Jan 1, 1970
                   </h2>
                 </div>
                 <hr
@@ -161,7 +161,7 @@ exports[`<MessageEditHistory /> should support events with 1`] = `
           >
             <li>
               <div
-                aria-label=",  NaN NaN"
+                aria-label="Thu, Jan 1, 1970"
                 class="mx_DateSeparator"
                 role="separator"
               >
@@ -175,7 +175,7 @@ exports[`<MessageEditHistory /> should support events with 1`] = `
                     aria-hidden="true"
                     class="mx_DateSeparator_dateHeading"
                   >
-                    ,  NaN NaN
+                    Thu, Jan 1, 1970
                   </h2>
                 </div>
                 <hr
@@ -193,7 +193,7 @@ exports[`<MessageEditHistory /> should support events with 1`] = `
                   <span
                     class="mx_MessageTimestamp"
                   >
-                    NaN:NaN
+                    00:00
                   </span>
                   <div
                     class="mx_EventTile_content"
@@ -236,7 +236,7 @@ exports[`<MessageEditHistory /> should support events with 1`] = `
                   <span
                     class="mx_MessageTimestamp"
                   >
-                    NaN:NaN
+                    00:00
                   </span>
                   <div
                     class="mx_EventTile_content"
@@ -290,7 +290,7 @@ exports[`<MessageEditHistory /> should support events with 1`] = `
                   <span
                     class="mx_MessageTimestamp"
                   >
-                    NaN:NaN
+                    00:00
                   </span>
                   <div
                     class="mx_EventTile_content"

test/components/views/messages/DateSeparator-test.tsx

@@ -60,11 +60,11 @@ describe("DateSeparator", () => {
 
     type TestCase = [string, number, string];
     const testCases: TestCase[] = [
-        ["the exact same moment", nowDate.getTime(), "Today"],
+        ["the exact same moment", nowDate.getTime(), "today"],
-        ["same day as current day", nowDate.getTime() - HOUR_MS, "Today"],
+        ["same day as current day", nowDate.getTime() - HOUR_MS, "today"],
-        ["day before the current day", nowDate.getTime() - HOUR_MS * 12, "Yesterday"],
+        ["day before the current day", nowDate.getTime() - HOUR_MS * 12, "yesterday"],
         ["2 days ago", nowDate.getTime() - DAY_MS * 2, "Wednesday"],
-        ["144 hours ago", nowDate.getTime() - HOUR_MS * 144, "Sat, Dec 11 2021"],
+        ["144 hours ago", nowDate.getTime() - HOUR_MS * 144, "Sat, Dec 11, 2021"],
         [
             "6 days ago, but less than 144h",
             new Date("Saturday Dec 11 2021 23:59:00 GMT+0100 (Central European Standard Time)").getTime(),

test/components/views/messages/__snapshots__/DateSeparator-test.tsx.snap

@@ -3,7 +3,7 @@
 exports[`DateSeparator renders the date separator correctly 1`] = `
 <DocumentFragment>
   <div
-    aria-label="Today"
+    aria-label="today"
     class="mx_DateSeparator"
     role="separator"
   >
@@ -17,7 +17,7 @@ exports[`DateSeparator renders the date separator correctly 1`] = `
         aria-hidden="true"
         class="mx_DateSeparator_dateHeading"
       >
-        Today
+        today
       </h2>
     </div>
     <hr
@@ -30,7 +30,7 @@ exports[`DateSeparator renders the date separator correctly 1`] = `
 exports[`DateSeparator when feature_jump_to_date is enabled renders the date separator correctly 1`] = `
 <DocumentFragment>
   <div
-    aria-label="Fri, Dec 17 2021"
+    aria-label="Fri, Dec 17, 2021"
     class="mx_DateSeparator"
     role="separator"
   >
@@ -50,7 +50,7 @@ exports[`DateSeparator when feature_jump_to_date is enabled renders the date sep
         aria-hidden="true"
         class="mx_DateSeparator_dateHeading"
       >
-        Fri, Dec 17 2021
+        Fri, Dec 17, 2021
       </h2>
       <div
         class="mx_DateSeparator_chevron"

test/components/views/rooms/SearchResultTile-test.tsx

@@ -93,7 +93,7 @@ describe("SearchResultTile", () => {
                         room_id: ROOM_ID,
                         content: { body: `Message #${i}` },
                         event_id: `$${i}:server`,
-                        origin_server_ts: undefined,
+                        origin_server_ts: i,
                     }),
             ),
         });

test/components/views/rooms/__snapshots__/PinnedEventTile-test.tsx.snap

@@ -51,7 +51,7 @@ exports[`<PinnedEventTile /> should render pinned event 1`] = `
       <span
         class="mx_MessageTimestamp mx_PinnedEventTile_timestamp"
       >
-        Thu, Jan 1 1970 00:00:00
+        Thu, Jan 1, 1970, 00:00
       </span>
       <div
         class="mx_AccessibleButton mx_AccessibleButton_hasKind mx_AccessibleButton_kind_link"

test/test-utils/beacon.ts

@@ -103,6 +103,7 @@ export const makeBeaconEvent = (
         room_id: roomId,
         sender,
         content: ContentHelpers.makeBeaconContent(geoUri, timestamp, beaconInfoId, description),
+        origin_server_ts: 0,
     });
 };
 

test/test-utils/location.ts

@@ -27,6 +27,7 @@ export const makeLegacyLocationEvent = (geoUri: string): MatrixEvent => {
             msgtype: "m.location",
             geo_uri: geoUri,
         },
+        origin_server_ts: 0,
     });
 };
 
@@ -41,6 +42,7 @@ export const makeLocationEvent = (geoUri: string, assetType?: LocationAssetType)
             "Human-readable label",
             assetType,
         ),
+        origin_server_ts: 0,
     });
 };
 

test/test-utils/test-utils.ts

@@ -538,6 +538,7 @@ export function mkMessage({
     }
     const message = msg ?? "Random->" + Math.random();
     const event: MakeEventProps = {
+        ts: 0,
         ...opts,
         type: "m.room.message",
         content: {

test/utils/DateUtils-test.ts

@@ -23,8 +23,224 @@ import {
     formatTimeLeft,
     formatPreciseDuration,
     formatLocalDateShort,
+    getDaysArray,
+    getMonthsArray,
+    formatFullDateNoDayNoTime,
+    formatTime,
+    formatFullTime,
+    formatFullDate,
+    formatFullDateNoTime,
+    formatDate,
+    HOUR_MS,
+    MINUTE_MS,
+    DAY_MS,
 } from "../../src/DateUtils";
 import { REPEATABLE_DATE, mockIntlDateTimeFormat, unmockIntlDateTimeFormat } from "../test-utils";
+import * as languageHandler from "../../src/languageHandler";
+
+describe("getDaysArray", () => {
+    it("should return Sunday-Saturday in long mode", () => {
+        expect(getDaysArray("long")).toMatchInlineSnapshot(`
+            [
+              "Sunday",
+              "Monday",
+              "Tuesday",
+              "Wednesday",
+              "Thursday",
+              "Friday",
+              "Saturday",
+            ]
+        `);
+    });
+    it("should return Sun-Sat in short mode", () => {
+        expect(getDaysArray("short")).toMatchInlineSnapshot(`
+            [
+              "Sun",
+              "Mon",
+              "Tue",
+              "Wed",
+              "Thu",
+              "Fri",
+              "Sat",
+            ]
+        `);
+    });
+    it("should return S-S in narrow mode", () => {
+        expect(getDaysArray("narrow")).toMatchInlineSnapshot(`
+            [
+              "S",
+              "M",
+              "T",
+              "W",
+              "T",
+              "F",
+              "S",
+            ]
+        `);
+    });
+});
+
+describe("getMonthsArray", () => {
+    it("should return January-December in long mode", () => {
+        expect(getMonthsArray("long")).toMatchInlineSnapshot(`
+            [
+              "January",
+              "February",
+              "March",
+              "April",
+              "May",
+              "June",
+              "July",
+              "August",
+              "September",
+              "October",
+              "November",
+              "December",
+            ]
+        `);
+    });
+    it("should return Jan-Dec in short mode", () => {
+        expect(getMonthsArray("short")).toMatchInlineSnapshot(`
+            [
+              "Jan",
+              "Feb",
+              "Mar",
+              "Apr",
+              "May",
+              "Jun",
+              "Jul",
+              "Aug",
+              "Sep",
+              "Oct",
+              "Nov",
+              "Dec",
+            ]
+        `);
+    });
+    it("should return J-D in narrow mode", () => {
+        expect(getMonthsArray("narrow")).toMatchInlineSnapshot(`
+            [
+              "J",
+              "F",
+              "M",
+              "A",
+              "M",
+              "J",
+              "J",
+              "A",
+              "S",
+              "O",
+              "N",
+              "D",
+            ]
+        `);
+    });
+    it("should return 1-12 in numeric mode", () => {
+        expect(getMonthsArray("numeric")).toMatchInlineSnapshot(`
+            [
+              "1",
+              "2",
+              "3",
+              "4",
+              "5",
+              "6",
+              "7",
+              "8",
+              "9",
+              "10",
+              "11",
+              "12",
+            ]
+        `);
+    });
+    it("should return 01-12 in 2-digit mode", () => {
+        expect(getMonthsArray("2-digit")).toMatchInlineSnapshot(`
+            [
+              "01",
+              "02",
+              "03",
+              "04",
+              "05",
+              "06",
+              "07",
+              "08",
+              "09",
+              "10",
+              "11",
+              "12",
+            ]
+        `);
+    });
+});
+
+describe("formatDate", () => {
+    beforeAll(() => {
+        jest.useFakeTimers();
+        jest.setSystemTime(REPEATABLE_DATE);
+    });
+
+    afterAll(() => {
+        jest.setSystemTime(jest.getRealSystemTime());
+        jest.useRealTimers();
+    });
+
+    it("should return time string if date is within same day", () => {
+        const date = new Date(REPEATABLE_DATE.getTime() + 2 * HOUR_MS + 12 * MINUTE_MS);
+        expect(formatDate(date, false, "en-GB")).toMatchInlineSnapshot(`"19:10"`);
+    });
+
+    it("should return time string with weekday if date is within last 6 days", () => {
+        const date = new Date(REPEATABLE_DATE.getTime() - 6 * DAY_MS + 2 * HOUR_MS + 12 * MINUTE_MS);
+        expect(formatDate(date, false, "en-GB")).toMatchInlineSnapshot(`"Fri 19:10"`);
+    });
+
+    it("should return time & date string without year if it is within the same year", () => {
+        const date = new Date(REPEATABLE_DATE.getTime() - 66 * DAY_MS + 2 * HOUR_MS + 12 * MINUTE_MS);
+        expect(formatDate(date, false, "en-GB")).toMatchInlineSnapshot(`"Mon, 12 Sept, 19:10"`);
+    });
+
+    it("should return full time & date string otherwise", () => {
+        const date = new Date(REPEATABLE_DATE.getTime() - 666 * DAY_MS + 2 * HOUR_MS + 12 * MINUTE_MS);
+        expect(formatDate(date, false, "en-GB")).toMatchInlineSnapshot(`"Wed, 20 Jan 2021, 19:10"`);
+    });
+});
+
+describe("formatFullDateNoTime", () => {
+    it("should match given locale en-GB", () => {
+        expect(formatFullDateNoTime(REPEATABLE_DATE, "en-GB")).toMatchInlineSnapshot(`"Thu, 17 Nov 2022"`);
+    });
+});
+
+describe("formatFullDate", () => {
+    it("correctly formats with seconds", () => {
+        expect(formatFullDate(REPEATABLE_DATE, true, true, "en-GB")).toMatchInlineSnapshot(
+            `"Thu, 17 Nov 2022, 4:58:32 pm"`,
+        );
+    });
+    it("correctly formats without seconds", () => {
+        expect(formatFullDate(REPEATABLE_DATE, false, false, "en-GB")).toMatchInlineSnapshot(
+            `"Thu, 17 Nov 2022, 16:58"`,
+        );
+    });
+});
+
+describe("formatFullTime", () => {
+    it("correctly formats 12 hour mode", () => {
+        expect(formatFullTime(REPEATABLE_DATE, true, "en-GB")).toMatchInlineSnapshot(`"4:58:32 pm"`);
+    });
+    it("correctly formats 24 hour mode", () => {
+        expect(formatFullTime(REPEATABLE_DATE, false, "en-GB")).toMatchInlineSnapshot(`"16:58:32"`);
+    });
+});
+
+describe("formatTime", () => {
+    it("correctly formats 12 hour mode", () => {
+        expect(formatTime(REPEATABLE_DATE, true, "en-GB")).toMatchInlineSnapshot(`"4:58 pm"`);
+    });
+    it("correctly formats 24 hour mode", () => {
+        expect(formatTime(REPEATABLE_DATE, false, "en-GB")).toMatchInlineSnapshot(`"16:58"`);
+    });
+});
 
 describe("formatSeconds", () => {
     it("correctly formats time with hours", () => {
@@ -43,16 +259,15 @@ describe("formatSeconds", () => {
 });
 
 describe("formatRelativeTime", () => {
-    let dateSpy: jest.SpyInstance<number, []>;
     beforeAll(() => {
-        dateSpy = jest
+        jest.useFakeTimers();
-            .spyOn(global.Date, "now")
         // Tuesday, 2 November 2021 11:18:03 UTC
-            .mockImplementation(() => 1635851883000);
+        jest.setSystemTime(1635851883000);
     });
 
     afterAll(() => {
-        dateSpy.mockRestore();
+        jest.setSystemTime(jest.getRealSystemTime());
+        jest.useRealTimers();
     });
 
     it("returns hour format for events created in the same day", () => {
@@ -71,7 +286,7 @@ describe("formatRelativeTime", () => {
         const date = new Date(2021, 10, 2, 11, 1, 23, 0);
         expect(formatRelativeTime(date)).toBe("11:01");
         expect(formatRelativeTime(date, false)).toBe("11:01");
-        expect(formatRelativeTime(date, true)).toBe("11:01AM");
+        expect(formatRelativeTime(date, true)).toBe("11:01 AM");
     });
 
     it("returns month and day for events created in the current year", () => {
@@ -134,6 +349,12 @@ describe("formatFullDateNoDayISO", () => {
     });
 });
 
+describe("formatFullDateNoDayNoTime", () => {
+    it("should return a date formatted for en-GB locale", () => {
+        expect(formatFullDateNoDayNoTime(REPEATABLE_DATE, "en-GB")).toMatchInlineSnapshot(`"17/11/2022"`);
+    });
+});
+
 describe("formatDateForInput", () => {
     it.each([["1993-11-01"], ["1066-10-14"], ["0571-04-22"], ["0062-02-05"]])(
         "should format %s",
@@ -162,15 +383,18 @@ describe("formatLocalDateShort()", () => {
     });
     const timestamp = new Date("Fri Dec 17 2021 09:09:00 GMT+0100 (Central European Standard Time)").getTime();
     it("formats date correctly by locale", () => {
+        const locale = jest.spyOn(languageHandler, "getUserLanguage");
+        mockIntlDateTimeFormat();
+
         // format is DD/MM/YY
-        mockIntlDateTimeFormat("en-UK");
+        locale.mockReturnValue("en-GB");
         expect(formatLocalDateShort(timestamp)).toEqual("17/12/21");
 
         // US date format is MM/DD/YY
-        mockIntlDateTimeFormat("en-US");
+        locale.mockReturnValue("en-US");
         expect(formatLocalDateShort(timestamp)).toEqual("12/17/21");
 
-        mockIntlDateTimeFormat("de-DE");
+        locale.mockReturnValue("de-DE");
         expect(formatLocalDateShort(timestamp)).toEqual("17.12.21");
     });
 });

test/utils/exportUtils/PlainTextExport-test.ts

@@ -49,8 +49,8 @@ describe("PlainTextExport", () => {
     });
 
     it.each([
-        [24, false, "Fri, Apr 16 2021 17:20:00 - @alice:example.com: Hello, world!\n"],
+        [24, false, "Fri, Apr 16, 2021, 17:20:00 - @alice:example.com: Hello, world!\n"],
-        [12, true, "Fri, Apr 16 2021 5:20:00PM - @alice:example.com: Hello, world!\n"],
+        [12, true, "Fri, Apr 16, 2021, 5:20:00 PM - @alice:example.com: Hello, world!\n"],
     ])("should return text with %i hr time format", async (hour: number, setting: boolean, expectedMessage: string) => {
         jest.spyOn(SettingsStore, "getValue").mockImplementation((settingName: string) =>
             settingName === "showTwelveHourTimestamps" ? setting : undefined,