D3 Course 1: Bar Chart
This example uses D3 v5 to visualize insertions and samples over time as a bar chart, a cursor ticker, and a blocking count curve. The main bar chart displays red and steel-blue rectangles representing sample and insert events, with linear scales mapping event start times and durations to x-positions and widths, while a band scale positions rows by assigned slot. Below, a stepped line generated with `d3.line` and `curveStep` shows cursor movement, and another line tracks blocking counts, both using `scaleLinear` and `axisLeft` with grid lines. Random data is generated programmatically in `data.js` and rendered to SVG.