UiEvent.pageX does not exixt

[chinedufn]

This code panics when I mouse over my canvas

 let on_mouse_move = Closure::wrap(Box::new(move |event: web_sys::MouseEvent| {
      web_sys::console::log_1(&"mouse moved".into());
      let x = event.page_x();
      let y = event.page_y();
  }) as Box<FnMut(_)>);

  canvas.add_event_listener_with_callback(
      "mousemove",
      on_mouse_move.as_ref().unchecked_ref(),
  )?;

  on_mouse_move.forget();

I have the MouseEvent and UiEvent features enabled.

I'm using wasm-bindgen 0.2.29

[alexcrichton]

Hm interesting! Looks like on Firefox Object.getOwnPropertyDescriptor(UIEvent.prototype, 'pageX') returns a descriptor, whereas on Chrome it does not. Are you using chrome perchance?

[chinedufn]

FWIW I switched to offset_x which works fine for my use case (I just needed some relative coordinates..)

Yup I was indeed using Chrome and I didn't check Firefox so that could be the problem!

[limira]

I look in the docs. It says that (emphasis added by me)

This property was never part of any standard, and was only implemented across a subset of browsers, and only for a limited number of versions. A standardized version of pageX was added to the MouseEvent interface, however, and is well-supported. You should not expect to find pageX on any non-mouse events. Do not look for pageX on any non-mouse events in new code and update existing code as soon as possible.

And in the Specifications Section:

This property is not part of any specification. See MouseEvent.pageX instead.

So may be just access MouseEvent.pageX directly, not via UiEvent.

[limira]

@chinedufn, I guess you import these things yourself (not using web-sys)??. I do a search on web-sys docs and it seems that page_x only available for UiEvent!

I think this is still an issue in web-sys!

[chinedufn]

I'm using web-sys but I thought you were suggesting that people should write their own extern block for this - haha sorry! Re-opened!

[alexcrichton]

Hm ok now that I look into this I think it's a bug that we're still using the old "structural" intepretation of field accesses throughout web-sys. After #1019 it's intended that web-sys switched over to just accessing properties directly, and not doing so is a bug we forgot to fix! I'll submit a fix for this shortly.