Customdata format variations

There seems to be a lot of variations regarding the format in which the customdata is structured.

Showcase:

library(plotly)
library(htmlwidgets)

js <- "function(el, x) {
         el.on('plotly_click', function(d) {
           console.log(d);
           console.log(d.points[0].data.customdata[0]);
       });
       }"

X <- data.frame(x = c(1, 2, 1, 2), y = c(1, 1, 2, 2), z = as.character(1:4), mydata = letters[1:4])

gg <- ggplot(X, aes(x = x, y = y, customdata = mydata)) + geom_tile(aes(fill = z))

ggplotly(gg) %>% onRender(js)

Same as above, except z is now numerical:

X <- data.frame(x = c(1, 2, 1, 2), y = c(1, 1, 2, 2), z = 1:4, mydata = letters[1:4])

More information in this Stackoverflow post.

Start by reproducing the two R examples using ggplotly() and htmlwidgets::onRender(), then inspect the customdata received in the plotly_click callback. The issue names no target files or tests and does not define the desired consistent format, so the expected behavior needs to be established before implementation.