src/charts/grouped-bar.js
function handleBarsMouseOver(e, d) {
            d3Selection.select(e)
                .attr('fill', () => d3Color.color(categoryColorMap[d.group]).darker());
        }
function handleBarsMouseOver(e, d) {
            d3Selection.select(e)
                .attr('fill', () => d3Color.color(categoryColorMap[d.group]).darker());
        }
function handleBarsMouseOver ( e , d ) { d3Selection . select ( e ) . attr ( 'fill' , ( ) => d3Color . color ( categoryColorMap [ d . group ] ) . darker ( ) ) ; }
Handles a mouseover event on top of a bar
@param  {obj} e the fired event
@param  {obj} d data of bar
@return {void}
Handles a mouseover event on top of a bar