This very lightweight and simple library is a way to show tabular data to your users and let them edit it. It's short enough that you might consider just modifying its source to add the features you need for your use case.
If you're using a bundler, run npm install nanosheets then import it with import {NanoSheets} from
"nanosheets".
This example show how data is saved. It's a simple object with cell coordinates as keys and cell content as value. Cells can only contain string value.
See changes on the left reflected on the right side. This just uses the same object for both editor's data, and lets them know when to redraw.