libreevent/website/src/contributing/packaging.md

Packaging

To be able to work on libreevent, you need to have node.js and npm installed on your computer.

Then, to set up the development environment, run

npm i

in the src/server, src/webapp/main and src/webapp/setup directories. This creates the node_modules folder in each of those directories. This is also what you need to do, if you want to upload the development version of libreevent.