This example demonstrates common JavaScript array operations using plain code and D3’s `ascending` comparator. It shows how functions like `range`, `forEach`, `filter`, `map`, `reduce`, and `sort` transform arrays, including sorting numeric values correctly and grouping entries by key. No visual output is rendered; the code logs intermediate results to the console. The example uses the `d3` library’s `ascending` function for stable sorts, building a practical reference for array manipulation basics.