Adding scale marker to Mapping module

I would like to display a scale marker on the map in the mapping module but am having trouble.

I am trying to add the code L.control.scale().addTo(map); to the Control.Scale.js file but am clearly doing it wrong since it is not working.

Not much of a leaflet/js person here. Can someone provide guidance?

On which map do you want to add a scale control? If you want to add one to the map on an item show page, open mapping-show.js and add your code to the file:

// ...
var map ='mapping-map', {
    fullscreenControl: true,
L.control.scale().addTo(map); // add this line
var markers = new L.FeatureGroup();
// ...