Having some kind of debugging tool in our belt is extremely useful before writing a lot of code. In this lesson we build a println!()-style syntax using JavaScript’s console.log to be able to log out values in Rust.

extern "C" {

    ...

    #[wasm_bindgen(js_namespace = console)]

    fn log(msg: &str);

}

#[wasm_bindgen]

pub fn run() {

    let val = document.createElement("p");

    log!("The {} is {}", "meaning of life", );

    val.set_inner_html("Hello from Rust!!!!!!");

    document.body().append_child(val);

}