diff --git a/files/en-us/web/javascript/reference/global_objects/date/gettimezoneoffset/index.md b/files/en-us/web/javascript/reference/global_objects/date/gettimezoneoffset/index.md index e6864eb0bc42a6f..9a891df6b2cc9ce 100644 --- a/files/en-us/web/javascript/reference/global_objects/date/gettimezoneoffset/index.md +++ b/files/en-us/web/javascript/reference/global_objects/date/gettimezoneoffset/index.md @@ -45,6 +45,8 @@ In a region that annually shifts in and out of Daylight Saving Time (DST), as `d > **Note:** `getTimezoneOffset()`'s behavior will never differ based on the time when the code is run — its behavior is always consistent when running in the same region. Only the value of `date` affects the result. +> **Note:** [Many countries have experimented with not changing the time twice a year](https://en.wikipedia.org/wiki/Daylight_saving_time_by_country#Past_observance) and this has meant that DST has continued over the winter too. For example in the UK DST lasted from 2:00AM 18 February 1968 to 3:00AM 31 October 1971, so during the winter the clocks were not set back. + In most implementations, the [IANA time zone database](https://en.wikipedia.org/wiki/Daylight_saving_time#IANA_time_zone_database) (tzdata) is used to precisely determine the offset of the local timezone at the moment of the `date`. However, if such information is unavailable, an implementation may return zero. ## Examples diff --git a/files/en-us/web/javascript/reference/global_objects/date/parse/index.md b/files/en-us/web/javascript/reference/global_objects/date/parse/index.md index cfc3f35478b43a3..815b04c6dff54a1 100644 --- a/files/en-us/web/javascript/reference/global_objects/date/parse/index.md +++ b/files/en-us/web/javascript/reference/global_objects/date/parse/index.md @@ -58,6 +58,8 @@ Date.parse("2019-01-01T00:00:00"); Implementations usually default to the local time zone when the date string is non-standard. For consistency, we will assume that the code uses the UTC timezone. +> **Note:** The local time zone offset comes from the system setting of the device and is then applied to the date being parsed. [Daylight Saving Time (DST), of the local time zone, can also have an effect on this too](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/getTimezoneOffset#varied_results_in_daylight_saving_time_dst_regions). + ```js Date.parse("Jan 1, 1970"); // 0 in all implementations @@ -75,12 +77,14 @@ Date.parse("Thu, 01 Jan 1970 00:00:00 GMT+0300"); // Single number Date.parse("0"); -// 946684800000 in Chrome (Sat Jan 01 2000 00:00:00 GMT+0000); -// NaN in Firefox; +// NaN in Firefox ≤122 +// 946684800000 in Chrome and Firefox ≥123 (Sat Jan 01 2000 00:00:00 GMT+0000); // -62167219200000 in Safari (Sat Jan 01 0000 00:00:00 GMT+0000) // Two-digit number that may be a month -Date.parse("28"); // NaN in all implementations +Date.parse("28"); +// NaN Chrome and Firefox +// -61283606400000 in Safari (Fri Dec 31 0027 23:58:45 GMT-0001) // Two-digit year Date.parse("70/01/01"); // 0 in all implementations @@ -91,8 +95,8 @@ Date.parse("Mar 32, 2014"); // NaN in all implementations Date.parse("2014/25/23"); // NaN in all implementations Date.parse("2014-02-30"); -// NaN in Safari and Firefox; -// 1393718400000 in Chrome (Sun Mar 02 2014 00:00:00 GMT+0000) +// NaN in Safari +// 1393718400000 in Chrome and Firefox (Sun Mar 02 2014 00:00:00 GMT+0000) Date.parse("02/30/2014"); // 1393718400000 in all implementations // Chrome, Safari, and Firefox 122 and later parse only the first three letters for the month.