binding for Date.prototype.getTimezoneOffset()

src/js.rs

@@ -886,6 +886,13 @@ extern "C" {
     #[wasm_bindgen(method, js_name = getTime)]
     pub fn get_time(this: &Date) -> f64;
 
+    /// The getTimezoneOffset() method returns the time zone difference, in minutes,
+    /// from current locale (host system settings) to UTC.
+    ///
+    /// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/getTimezoneOffset
+    #[wasm_bindgen(method, js_name = getTimezoneOffset)]
+    pub fn get_timezone_offset(this: &Date) -> f64;
+
     /// Creates a JavaScript Date instance that represents
     /// a single moment in time. Date objects are based on a time value that is
     /// the number of milliseconds since 1 January 1970 UTC.

tests/all/js_globals/Date.rs

@@ -312,6 +312,42 @@ fn get_time() {
         .test()
 }
 
+#[test]
+fn get_timezone_offset() {
+    project()
+        .file(
+            "src/lib.rs",
+            r#"
+            #![feature(proc_macro, wasm_custom_section)]
+
+            extern crate wasm_bindgen;
+            use wasm_bindgen::prelude::*;
+            use wasm_bindgen::js::Date;
+
+            #[wasm_bindgen]
+            pub fn get_timezone_offset(this: &Date) -> f64 {
+                this.get_timezone_offset()
+            }
+        "#,
+        )
+        .file(
+            "test.js",
+            r#"
+            import * as assert from "assert";
+            import * as wasm from "./out";
+
+            export function test() {
+                let date1 = new Date('August 19, 1975 23:15:30 GMT+07:00');
+                let date2 = new Date('August 19, 1975 23:15:30 GMT-02:00');
+
+                assert.equal(typeof wasm.get_timezone_offset(date1), "number");
+                assert.equal(wasm.get_timezone_offset(date1), wasm.get_timezone_offset(date2));
+            }
+        "#,
+        )
+        .test()
+}
+
 #[test]
 fn new() {
     project()