Hi all,
I have been looking for a javascript library to make spreadsheets in custom webapps.
Finally i found a project called Handsontable https://handsontable.com/
I have not tried out every feature but there seem to be basic functionallity of eg google sheets 
For everyone who is interested, please have a look at my implementation of the library in anvil using the clone link below.
Link to their docs:
Link to live project:
Clone link