This example shows electronic sales from 2013 to 2021 with a combined line and area chart. The visualization overlays a smooth black line representing yearly sales trends with a green filled area beneath it, using d3.line(), d3.area(), and curveBasis for interpolation. The SVG chart uses d3.scaleTime and d3.scaleLinear for axes, with d3.axisLeft and d3.axisBottom adding gridlines and labels. Data is loaded as CSV from a GitHub gist, parsed with d3.timeParse, and rendered using D3 v5.