[BUG] Formatter "opts" does not appear to work

[daveomcd]

I am wanting to display a value on my data labels that is different from the charted data. So I made a collection that matches the x-axis labels that I wanted to pull from given the index value.

I found this documentation here for the "formatter": Apex Charts Data Labels Documentation

Discussed there is an "opts" parameter that seems to be what I want. However, I am getting an error when I attempt to use it. Is this not supported? Or am I doing something incorrectly?

I'm on Rails 5.1.6. Relevant gems installed: apexcharts, functionable-json

dataLabels: { 
    enabled: false, 
    formatter: function(val,opts) { return ((val == null) ? '' : '$ ') + parseFloat(val).toLocaleString().substring(0,parseFloat(val).toLocaleString().length-4); } 
  },

Error:
undefined local variable or method `opts' for #<#Class:0x00007faab8427b50:0x00007faaa9cfb588>