[vega 3.0] view.on generates error

When writing a simple custom event listener, we get the following error:

view.on(view.events('view', 'mouseover'), e => {
  console.log(e);
});

It seems to come from onStream method which expects the callback to return something:

func = function(e) {
  df.touch(target(e)); // breaks when target(e) is undefined
};

If you’d like (and it is a proper fix) I can create a PR with this change:

func = function(e) {
  var t = target(e);
  if (t) {
    df.touch(t);
  }
};

[jheer]

I’ve now updated the porting guide. I’ve also extended the Vega View class with new methods:

• addEventListener / removeEventListener (for traditional input event callbacks)
• addSignalListener / removeSignalListener (which replace the v2 onSignal / offSignal methods)

[floribon]

That’s really great, thanks a lot!