World Countries Tree
This visualization shows the hierarchical structure of world countries, organized by continent and subregion, as a horizontal tree layout. The code uses D3 v5’s `tree` and `hierarchy` functions to position nodes and `linkHorizontal` to draw connecting paths in SVG. Text labels display country names at varying font sizes based on depth, and the entire view supports zooming via d3.zoom. The data comes from a local JSON file listing regions and their member nations.