I am trying to create a highcharter graph that allows for a user to hover over the y-axis labels and have a tooltip show up with some information.

I have found this highcharts example in jsfiddle http://jsfiddle.net/W5wag/2/ that demonstrates what I am trying to do.

Here is a very basic example of what I am trying to do in R using highcharter but it isn't working:

  mtcars %>%
    hchart('scatter', hcaes(x = mpg, y = wt)) %>% 
    hc_xAxis(
      labels = list(
        enabled = TRUE,
        formatter = JS("function(){
          return '<span title='My custom title'>' + this.value + '</span>';
        }"
        )
      )
    )

Can anybody shed some light on what I am doing wrong?