mholt/PapaParse ? reverse-engineered prompt

Build me a JavaScript library that can parse CSV files quickly and reliably in the browser and in Node.

I want it to handle normal CSV, weird edge cases, big files, quoted values, line breaks inside cells, and malformed input without breaking. It should work with local files, text strings, and streams, and it should also be able to turn JSON data back into CSV. If possible, make it smart enough to figure out the delimiter on its own, support headers, and let me pause, resume, or stop parsing while it runs. It would be great if it could use workers in the browser so the page stays responsive, and if it can automatically convert obvious numbers and booleans into the right types.

Please include a simple API like parse and unparse, add tests, and make sure the code is clean and easy to use. If you need to check current browser or Node docs while building it, go ahead.