Add a top-level web_sys::window function

Returns `Option<Window>` and can be used as a convenience to get a handle to the
global `window` object.

crates/web-sys/src/lib.rs

@@ -17,4 +17,15 @@ extern crate wasm_bindgen;
 extern crate js_sys;
 use js_sys::Object;
 
+#[cfg(feature = "Window")]
+pub fn window() -> Option<Window> {
+    use wasm_bindgen::{JsValue, JsCast};
+
+    js_sys::Function::new_no_args("return this")
+        .call0(&JsValue::undefined())
+        .ok()?
+        .dyn_into::<Window>()
+        .ok()
+}
+
 include!(concat!(env!("OUT_DIR"), "/bindings.rs"));

examples/canvas/src/lib.rs

@@ -8,7 +8,7 @@ use wasm_bindgen::JsCast;
 
 #[wasm_bindgen]
 pub fn draw() {
-    let document = web_sys::Window::document().unwrap();
+    let document = web_sys::window().unwrap().document().unwrap();
     let canvas = document.get_element_by_id("canvas").unwrap();
     let canvas: web_sys::HtmlCanvasElement = canvas
         .dyn_into::<web_sys::HtmlCanvasElement>()

examples/fetch/build.sh

@@ -8,3 +8,6 @@ cargo +nightly build --target wasm32-unknown-unknown
 cargo +nightly run --manifest-path ../../crates/cli/Cargo.toml \
   --bin wasm-bindgen -- \
   ../../target/wasm32-unknown-unknown/debug/fetch.wasm --out-dir .
+
+npm install
+npm run serve

examples/fetch/src/lib.rs

@@ -12,7 +12,7 @@ use wasm_bindgen::prelude::*;
 use wasm_bindgen::JsCast;
 use wasm_bindgen_futures::future_to_promise;
 use wasm_bindgen_futures::JsFuture;
-use web_sys::{Request, RequestInit, RequestMode, Response, Window};
+use web_sys::{Request, RequestInit, RequestMode, Response};
 
 /// A struct to hold some data from the github Branch API.
 ///
@@ -57,7 +57,8 @@ pub fn run() -> Promise {
         .set("Accept", "application/vnd.github.v3+json")
         .unwrap();
 
-    let request_promise = Window::fetch_with_request(&request);
+    let window = web_sys::window().unwrap();
+    let request_promise = window.fetch_with_request(&request);
 
     let future = JsFuture::from(request_promise)
         .and_then(|resp_value| {

examples/paint/src/lib.rs

@@ -9,7 +9,7 @@ use wasm_bindgen::JsCast;
 
 #[wasm_bindgen]
 pub fn main() {
-    let document = web_sys::Window::document().unwrap();
+    let document = web_sys::window().unwrap().document().unwrap();
     let canvas = document
         .create_element("canvas")
         .unwrap()