diff --git a/src/offset/mod.rs b/src/offset/mod.rs index 09f6821d..f24a15df 100644 --- a/src/offset/mod.rs +++ b/src/offset/mod.rs @@ -46,6 +46,26 @@ pub use self::utc::Utc; /// DST. /// * No result when the clock is turned forwards during a transition due to for example DST. /// +///
+/// +/// In wasm, when using [`Local`], only the [`LocalResult::Single`] variant is returned. +/// Specifically: +/// +/// * When the clock is turned backwards, where `Ambiguous(earliest, latest)` would be expected, +/// `Single(earliest)` is returned instead. +/// * When the clock is turned forwards, where `None` would be expected, `Single(t)` is returned, +/// with `t` being the requested local time represented as though there is no transition on that +/// day (i.e. still "summer time") +/// +/// This is caused because of limitations in the JavaScript +/// [`Date`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date) +/// API, which always parses a local time as a single, valid time - even for an +/// input which describes a nonexistent or ambiguous time. +/// +/// See further discussion and workarounds in . +/// +///
+/// /// When the clock is turned backwards it creates a _fold_ in local time, during which the local /// time is _ambiguous_. When the clock is turned forwards it creates a _gap_ in local time, during /// which the local time is _missing_, or does not exist.