Choropleth Map
This choropleth map colors countries by economic classification, with a color legend and zooming and panning via d3.zoom. It loads world geometry from TopoJSON and country names from TSV data, joining them by ID. The map uses a natural Earth projection via d3.geoNaturalEarth1 and d3.geoPath, with an ordinal color scale based on d3.scaleOrdinal and a spectral scheme. Hovering highlights countries, and a custom color legend is built with reusable SVG components.