Let's make a map with D3.js!
This example renders a hierarchical tree visualization of world regions and countries using D3.js v5. The data is loaded from a JSON file that organizes countries under continents and subregions, which is then processed with the `d3.hierarchy` and `d3.tree` layouts. SVG paths are generated for the links using `d3.linkVertical`, with the tree layout’s size set to the full browser window dimensions. The map-like structure is drawn solely as a node-link diagram, not a geographic projection.