This example visualizes the distribution of JavaScript event listeners attached to DOM nodes on the BBC and CNN homepages using data from JSON dumps supplied in the gist. It shows which event types occur most frequently and how many listeners are registered per element, with node IDs and tag names labeled directly in the visualization. The React-based interface renders the listener counts using D3’s hierarchical layout and color-coded circles, while node-specific data is processed from the `listenerCount` and `listenersPerNode` objects. The code relies on `d3.hierarchy` and `d3.pack` to generate the bubble chart from the provided JSON files.