readme.md
In vegawidget: 'Htmlwidget' for 'Vega' and 'Vega-Lite'

This example shows how we can design a chart using Vega-Lite, then use Shiny to return the data behind a graphical mark when that mark is clicked, by directing Vega to listen to "click" events.

In the server function, we use vw_shiny_get_event() to return the data behind a mark, whenever that mark is clicked. We specify that the event to be listened-to is "click". We also have to tell Vega what to do when it receives a click-event; we do this using a JavaScript event-handler.

To make things a little bit easier, this package provides a handler-library, so you can specify to use the "datum" handler, which returns a list of the data-observation (datum) associated with the current location of the cursor. You need only specify the body of a function that returns the value that you want sent Shiny, the vw_shiny_get_event() function takes care of the rest of the JavaScript.