Hi there,
It depends on what you want to do. While both Leaflet and NodeJS are Javascript based, Leaflet is mostly a frontend library used to render map tiles, markers and other geographical features, whereas NodeJS is a backend server framework.
You could use these two together in multiple ways:
- integrate Leaflet in your frontend pages, have your NodeJS output GeoJSON which is directly usable on Leaflet, if what you're interested is showing database/dynamic geographical features (lat lng points, shapes, etc.).
If you have any questions you should further clarify the scope of your project a bit.