Add {Utc,Local}::now() constructor versions for the `wasm32` arch

While likely providing only incomplete support for WebAssembly, this
commit opens up chrono for use on the wasm32 architecture.

Cargo.toml

@@ -35,6 +35,12 @@ num-traits = { version = "0.2", default-features = false }
 rustc-serialize = { version = "0.3.20", optional = true }
 serde = { version = "1", optional = true }
 
+[target.'cfg(target_arch = "wasm32")'.dependencies]
+wasm-bindgen = { version = "0.2" }
+js-sys = "0.3" # contains FFI bindings for the JS Date API
+
+
+
 [dev-dependencies]
 serde_json = { version = "1" }
 serde_derive = { version = "1" }

src/lib.rs

@@ -414,6 +414,10 @@ extern crate serde as serdelib;
 #[cfg(test)]
 #[macro_use]
 extern crate doc_comment;
+#[cfg(target_arch = "wasm32")]
+extern crate wasm_bindgen;
+#[cfg(target_arch = "wasm32")]
+extern crate js_sys;
 
 #[cfg(test)]
 doctest!("../README.md");

src/offset/local.rs

@@ -87,9 +87,18 @@ impl Local {
     }
 
     /// Returns a `DateTime` which corresponds to the current date.
+    #[cfg(not(target_arch = "wasm32"))]
     pub fn now() -> DateTime<Local> {
         tm_to_datetime(oldtime::now())
     }
+
+    /// Returns a `DateTime` which corresponds to the current date.
+    #[cfg(target_arch = "wasm32")]
+    pub fn now() -> DateTime<Local> {
+        use super::Utc;
+        let now: DateTime<Utc> = super::Utc::now();
+        now.with_timezone(&Local)
+    }
 }
 
 impl TimeZone for Local {
@@ -179,4 +188,3 @@ mod tests {
                 "unexpected timestr {:?}", timestr);
     }
 }
-

src/offset/utc.rs

@@ -4,7 +4,7 @@
 //! The UTC (Coordinated Universal Time) time zone.
 
 use std::fmt;
-#[cfg(feature="clock")]
+#[cfg(all(feature="clock", not(target_arch = "wasm32")))]
 use oldtime;
 
 use naive::{NaiveDate, NaiveDateTime};
@@ -38,11 +38,23 @@ impl Utc {
     pub fn today() -> Date<Utc> { Utc::now().date() }
 
     /// Returns a `DateTime` which corresponds to the current date.
+    #[cfg(not(target_arch = "wasm32"))]
     pub fn now() -> DateTime<Utc> {
         let spec = oldtime::get_time();
         let naive = NaiveDateTime::from_timestamp(spec.sec, spec.nsec as u32);
         DateTime::from_utc(naive, Utc)
     }
+
+    /// Returns a `DateTime` which corresponds to the current date.
+    #[cfg(target_arch = "wasm32")]
+    pub fn now() -> DateTime<Utc> {
+        let now = js_sys::Date::new_0();
+        let millisecs_since_unix_epoch: u64 = now.get_time() as u64;
+        let secs  = millisecs_since_unix_epoch / 1000;
+        let nanos = 1_000_000 * (millisecs_since_unix_epoch - 1000 * secs);
+        let naive = NaiveDateTime::from_timestamp(secs as i64, nanos as u32);
+        DateTime::from_utc(naive, Utc)
+    }
 }
 
 impl TimeZone for Utc {
@@ -72,4 +84,3 @@ impl fmt::Debug for Utc {
 impl fmt::Display for Utc {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { write!(f, "UTC") }
 }
-