Add current_local_offset

Cargo.toml

@@ -3,6 +3,9 @@ name = "crosstime"
 version = "0.1.1"
 edition = "2021"
 
+[features]
+local-offset = [ "time/local-offset" ]
+
 [dependencies]
 time = "0.3"
 

src/lib.rs

@@ -11,3 +11,18 @@ pub fn now_utc() -> OffsetDateTime {
 pub fn now_utc() -> OffsetDateTime {
     return OffsetDateTime::now_utc();
 }
+
+#[cfg(feature = "local-offset")]
+#[cfg(target_arch = "wasm32")]
+pub fn current_local_offset() -> Result<time::UtcOffset, time::error::IndeterminateOffset> {
+    // get_timezone_offset is in minutes
+    time::UtcOffset::from_whole_seconds((js_sys::Date::new_0().get_timezone_offset() * 60f64) as i32)
+        .map_err(|_| time::error::IndeterminateOffset)
+}
+
+#[cfg(feature = "local-offset")]
+#[cfg(not(target_arch = "wasm32"))]
+#[inline(always)]
+pub fn current_local_offset() -> Result<time::UtcOffset, time::error::IndeterminateOffset> {
+    time::UtcOffset::current_local_offset()
+}