Making a bar chart
This example shows a basic bar chart placeholder using population data from a CSV file. It loads the data with `d3.csv` and applies a linear scale with `scaleLinear` to map population values, though the scale is not yet used for positioning. The code creates SVG rectangles with `selectAll('rect').data().enter().append('rect')`, each with fixed dimensions of 300 by 200 pixels. The rendering relies on D3 v5 and SVG output, with the chart structure defined in `index.html` and populated from `bundle.js`.