This example demonstrates data cleaning of a CSV file containing survey responses about favorite days of the week. The code uses D3.js version 5’s `d3.csv` to fetch the external dataset from a VizHub URL, then applies a series of `Array.filter` calls to remove invalid entries such as empty strings, dates, and non-day answers. After cleaning, `Array.map` standardizes the responses by capitalizing the first letter of each day name. The processed data is logged to the browser console for inspection.