src/charts/brush.js
function handleBrushStart() {
            const selection = d3Selection.event.selection;

            if (!selection) {
                return;
            }

            dispatcher.call('customBrushStart', this, selection.map(xScale.invert));
        }
function handleBrushStart() {
            const selection = d3Selection.event.selection;

            if (!selection) {
                return;
            }

            dispatcher.call('customBrushStart', this, selection.map(xScale.invert));
        }
function handleBrushStart ( ) { const selection = d3Selection . event . selection ; if ( ! selection ) { return ; } dispatcher . call ( 'customBrushStart' , this , selection . map ( xScale . invert ) ) ; }
When a brush event starts, we can extract info from the extension
of the brush.

@return {void}
When a brush event starts we can extract info from the extension of the brush .