js-sys: Add bindings for WebAssembly.instantiate

Part of rustwasm#275

Author: fitzgen

crates/js-sys/src/lib.rs

@@ -2866,6 +2866,20 @@ pub mod WebAssembly {
         #[wasm_bindgen(js_namespace = WebAssembly)]
         pub fn compile(buffer_source: &JsValue) -> Promise;
 
+        /// The `WebAssembly.instantiate()` function allows you to compile and
+        /// instantiate WebAssembly code.
+        ///
+        /// [MDN documentation](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WebAssembly/instantiate)
+        #[wasm_bindgen(js_namespace = WebAssembly, js_name = instantiate)]
+        pub fn instantiate_buffer(buffer: &[u8], imports: &Object) -> Promise;
+
+        /// The `WebAssembly.instantiate()` function allows you to compile and
+        /// instantiate WebAssembly code.
+        ///
+        /// [MDN documentation](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WebAssembly/instantiate)
+        #[wasm_bindgen(js_namespace = WebAssembly, js_name = instantiate)]
+        pub fn instantiate_module(module: &Module, imports: &Object) -> Promise;
+
         /// The `WebAssembly.validate()` function validates a given typed
         /// array of WebAssembly binary code, returning whether the bytes
         /// form a valid wasm module (`true`) or not (`false`).

crates/js-sys/tests/wasm/WebAssembly.rs

@@ -172,6 +172,17 @@ fn webassembly_instance() {
     assert!(Reflect::has(exports.as_ref(), &"exported_func".into()));
 }
 
+#[wasm_bindgen_test(async)]
+fn instantiate_module() -> impl Future<Item = (), Error = JsValue> {
+    let module = WebAssembly::Module::new(&get_valid_wasm()).unwrap();
+    let imports = get_imports();
+    let p = WebAssembly::instantiate_module(&module, &imports);
+    JsFuture::from(p)
+        .map(|inst| {
+            assert!(inst.is_instance_of::<WebAssembly::Instance>());
+        })
+}
+
 #[wasm_bindgen_test]
 fn memory_works() {
     let obj = Object::new();