As much as I’d rather use open source software, Excel is still the simplest solution. Unfortunately, Excel spreadsheets are XLSX files. XLSX is a rather complex XML format and difficult to parse. I looked for an NPM module to read XLSX files, but haven’t found one I liked.
After considerable head scratching, I realized R ( https://www.r-project.org/) is specifically designed to process tabular data from all sorts of sources. I decided to write a simple R script to do the conversion.