Add an example of importing non-browser functions

Closes #208

examples/import_js/src/lib.rs

@@ -0,0 +1,39 @@
+#![feature(proc_macro, wasm_custom_section, wasm_import_module)]
+
+extern crate wasm_bindgen;
+
+use wasm_bindgen::prelude::*;
+
+#[wasm_bindgen(module = "./defined-in-js")]
+extern {
+    fn name() -> String;
+
+    type MyClass;
+
+    #[wasm_bindgen(constructor)]
+    fn new() -> MyClass;
+
+    #[wasm_bindgen(method, getter)]
+    fn number(this: &MyClass) -> u32;
+    #[wasm_bindgen(method, setter)]
+    fn set_number(this: &MyClass, number: u32) -> MyClass;
+    #[wasm_bindgen(method)]
+    fn render(this: &MyClass) -> String;
+}
+
+// Import `console.log` so we can log something to the console
+#[wasm_bindgen]
+extern {
+    #[wasm_bindgen(js_namespace = console)]
+    fn log(s: &str);
+}
+
+#[wasm_bindgen]
+pub fn run() {
+    log(&format!("Hello, {}!", name()));
+
+    let x = MyClass::new();
+    assert_eq!(x.number(), 42);
+    x.set_number(10);
+    log(&x.render());
+}