Scrollama uses the scrollama library and D3 v7 to create a scrollytelling experience where line charts of COVID-19 case totals by region update as the user scrolls through steps. The visualization shows cumulative case counts over time, with each region’s data rendered as an SVG path using d3.line and d3.curveMonotoneX. Scrolling triggers updatePlot to redraw the chart with a growing subset of regions, while the axis labels and tick formatting use d3.axisBottom and d3.timeFormat. Data comes from a remote JSON file of COVID-19 cases.