The two functions used to create a click event handler for the Rust Click button

click.rs

// click_examples_init is called from the init() function in src/lib.rs 
// it is responsible for registering a click event handler. If there is no
// element found with the given id, then an alert button is displayed with
// an error message
pub fn click_examples_init(elem_id: String, txt_id: String) {
    match super::get_element_by_id(&elem_id) {
        Some(btn) => register_click_handler(btn.as_ref() as &web_sys::EventTarget, txt_id),
        None => super::alert(&format!("No element was found with the id {}", elem_id)),
    };
}

// register_click_handler first creates the closure that will handle the event
// then it adds the listener to the button
fn register_click_handler(btn: &web_sys::EventTarget, txt_id: String) {
    let btn_closure = Closure::wrap(Box::new(move |evt: web_sys::MouseEvent| {
        set_inner_text(&txt_id, evt, "[rust handler]");
    }) as Box<FnMut(_)>);

    btn.add_event_listener_with_callback("click", btn_closure.as_ref().unchecked_ref())
        .unwrap();

    btn_closure.forget();
}