fix(common): date is not correctly formatted when year is between 0 and 99 (#40448)

use setFullYear method when parsing date to avoid javascript date factory behaviour

Fixes #40377

PR Close #40448

packages/common/src/i18n/format_date.ts

@@ -101,6 +101,38 @@ export function formatDate(
   return text;
 }
 
+/**
+ * Create a new Date object with the given date value, and the time set to midnight.
+ *
+ * We cannot use `new Date(year, month, date)` because it maps years between 0 and 99 to 1900-1999.
+ * See: https://github.com/angular/angular/issues/40377
+ *
+ * Note that this function returns a Date object whose time is midnight in the current locale's
+ * timezone. In the future we might want to change this to be midnight in UTC, but this would be a
+ * considerable breaking change.
+ */
+function createDate(year: number, month: number, date: number): Date {
+  // The `newDate` is set to midnight (UTC) on January 1st 1970.
+  // - In PST this will be December 31st 1969 at 4pm.
+  // - In GMT this will be January 1st 1970 at 1am.
+  // Note that they even have different years, dates and months!
+  const newDate = new Date(0);
+
+  // `setFullYear()` allows years like 0001 to be set correctly. This function does not
+  // change the internal time of the date.
+  // Consider calling `setFullYear(2019, 8, 20)` (September 20, 2019).
+  // - In PST this will now be September 20, 2019 at 4pm
+  // - In GMT this will now be September 20, 2019 at 1am
+
+  newDate.setFullYear(year, month, date);
+  // We want the final date to be at local midnight, so we reset the time.
+  // - In PST this will now be September 20, 2019 at 12am
+  // - In GMT this will now be September 20, 2019 at 12am
+  newDate.setHours(0, 0, 0);
+
+  return newDate;
+}
+
 function getNamedFormat(locale: string, format: string): string {
   const localeId = getLocaleId(locale);
   NAMED_FORMATS[localeId] = NAMED_FORMATS[localeId] || {};
@@ -362,13 +394,13 @@ function timeZoneGetter(width: ZoneWidth): DateFormatter {
 const JANUARY = 0;
 const THURSDAY = 4;
 function getFirstThursdayOfYear(year: number) {
-  const firstDayOfYear = (new Date(year, JANUARY, 1)).getDay();
+  const firstDayOfYear = createDate(year, JANUARY, 1).getDay();
-  return new Date(
+  return createDate(
       year, 0, 1 + ((firstDayOfYear <= THURSDAY) ? THURSDAY : THURSDAY + 7) - firstDayOfYear);
 }
 
 function getThursdayThisWeek(datetime: Date) {
-  return new Date(
+  return createDate(
       datetime.getFullYear(), datetime.getMonth(),
       datetime.getDate() + (THURSDAY - datetime.getDay()));
 }
@@ -720,7 +752,7 @@ export function toDate(value: string|number|Date): Date {
       is applied.
       Note: ISO months are 0 for January, 1 for February, ... */
       const [y, m = 1, d = 1] = value.split('-').map((val: string) => +val);
-      return new Date(y, m - 1, d);
+      return createDate(y, m - 1, d);
     }
 
     const parsedNb = parseFloat(value);

packages/common/src/pipes/date_pipe.ts

@@ -114,7 +114,6 @@ import {invalidPipeArgumentError} from './invalid_pipe_argument_error';
  *  |                    | O, OO & OOO | Short localized GMT format                                    | GMT-8                                                      |
  *  |                    | OOOO        | Long localized GMT format                                     | GMT-08:00                                                  |
  *
- * Note that timezone correction is not applied to an ISO string that has no time component, such as "2016-09-19"
  *
  * ### Format examples
  *

packages/common/test/i18n/format_date_spec.ts

@@ -347,6 +347,32 @@ describe('Format date', () => {
           .toEqual('10:14 AM');
     });
 
+    // The following test is disabled because backwards compatibility requires that date-only ISO
+    // strings are parsed with the local timezone.
+
+    // it('should create UTC date objects when an ISO string is passed with no time components',
+    //    () => {
+    //      expect(formatDate('2019-09-20', `MMM d, y, h:mm:ss a ZZZZZ`, ɵDEFAULT_LOCALE_ID))
+    //          .toEqual('Sep 20, 2019, 12:00:00 AM Z');
+    //    });
+
+    // This test is to ensure backward compatibility for parsing date-only ISO strings.
+    it('should create local timezone date objects when an ISO string is passed with no time components',
+       () => {
+         // Dates created with individual components are evaluated against the local timezone. See
+         // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/Date#Individual_date_and_time_component_values
+         const localDate = new Date(2019, 8, 20, 0, 0, 0, 0);
+         expect(formatDate('2019-09-20', `MMM d, y, h:mm:ss a ZZZZZ`, ɵDEFAULT_LOCALE_ID))
+             .toEqual(formatDate(localDate, `MMM d, y, h:mm:ss a ZZZZZ`, ɵDEFAULT_LOCALE_ID));
+       });
+
+    it('should create local timezone date objects when an ISO string is passed with time components',
+       () => {
+         const localDate = new Date(2019, 8, 20, 0, 0, 0, 0);
+         expect(formatDate('2019-09-20T00:00:00', `MMM d, y, h:mm:ss a ZZZZZ`, ɵDEFAULT_LOCALE_ID))
+             .toEqual(formatDate(localDate, `MMM d, y, h:mm:ss a ZZZZZ`, ɵDEFAULT_LOCALE_ID));
+       });
+
     it('should remove bidi control characters',
        () => expect(formatDate(date, 'MM/dd/yyyy', ɵDEFAULT_LOCALE_ID)!.length).toEqual(10));
 
@@ -389,6 +415,17 @@ describe('Format date', () => {
          expect(formatDate('2013-12-29', 'YYYY', 'en')).toEqual('2014');
          expect(formatDate('2010-01-02', 'YYYY', 'en')).toEqual('2009');
          expect(formatDate('2010-01-04', 'YYYY', 'en')).toEqual('2010');
+         expect(formatDate('0049-01-01', 'YYYY', 'en')).toEqual('0048');
+         expect(formatDate('0049-01-04', 'YYYY', 'en')).toEqual('0049');
+       });
+
+    // https://github.com/angular/angular/issues/40377
+    it('should format date with year between 0 and 99 correctly', () => {
+      expect(formatDate('0098-01-11', 'YYYY', ɵDEFAULT_LOCALE_ID)).toEqual('0098');
+      expect(formatDate('0099-01-11', 'YYYY', ɵDEFAULT_LOCALE_ID)).toEqual('0099');
+      expect(formatDate('0100-01-11', 'YYYY', ɵDEFAULT_LOCALE_ID)).toEqual('0100');
+      expect(formatDate('0001-01-11', 'YYYY', ɵDEFAULT_LOCALE_ID)).toEqual('0001');
+      expect(formatDate('0000-01-11', 'YYYY', ɵDEFAULT_LOCALE_ID)).toEqual('0000');
     });
   });
 });