This example demonstrates fundamental JavaScript array methods—forEach, filter, map, sort, and reduce—applied in a minimal React-based HTML page. The code shows how to transform an array of objects with key-value pairs using reduce to group entries, and sorts them with a custom comparator that compares object keys. It imports `ascending` from D3 v6.6.2 for potential sorting use, while other operations are commented out as templates. The page renders a large "Hello HTML!" message centered via CSS, with the array manipulation logic present but producing no visible output.