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| -rw-r--r-- | src/qml/doc/src/javascript/date.qdoc | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/src/qml/doc/src/javascript/date.qdoc b/src/qml/doc/src/javascript/date.qdoc index 4f897af928..4e1e3e55f5 100644 --- a/src/qml/doc/src/javascript/date.qdoc +++ b/src/qml/doc/src/javascript/date.qdoc @@ -132,6 +132,25 @@ hour, if DST is currently in effect, while it was not for the time specified, or vice versa. + Note: There are different date formats with different understandings of negative years. Common + human language does not have a year 0. The year after 1BC is 1AD. This understanding is + reflected when printing or parsing dates in one of the formats not standardized by ECMAScript. + That is: toString(), toLocaleString(), toUTCString() and friends. ECMAScript does standardize + one format: ISO 8601. This is what you get when you call toISOString(). This format does include + a year 0, which is 1BC in other formats. Thus you get different years when printing negative + dates with toISOString() and toString(). + + When setting the year using the Date constructor or set(UTC)FullYear(), the convention set by + ISO 8601 is used and 0 is a valid year. This means negative years set with the constructor or + set(UTC)FullYear() are zero-based and thus offset by one year from what is printed with + toString() and friends. Parsing the output of any of the to*String() methods will yield the same + date value you printed from. Date.parse() will recognize the different formats and their + convention on the existence of year 0. + + Note that all this is different from what you get in other JavaScript implementations which + usually treat year 0 as valid in all string representations. As the date formats are + "implementation-dependent" in the ECMAScript standard, this is still valid, though. + \sa {QtQml::Locale}{Locale} */ |