World Countries Tree
This interactive visualization displays a hierarchical tree of world countries, organized by continent and subregion. Using the D3.js library (v5), it renders a static radial tree layout using SVG elements. The code appends circles for each node and links to connect parents to children, with node sizes derived from a custom radius attribute. A zooming feature is enabled via the `zoom` event, allowing users to pan and scale the entire viewport. The data is structured as a nested JSON object with "World" as the root, containing continents, subregions, and individual country names as leaf nodes.