Facing error "Failed to load resource: the server responded with a status of 404 (Not Found)" in web browse console

Hi, I am using sublime text editor for writing js and server.

I am running the server code through cmd window. and opening http//:localhost:3000 in google chrome and webpage doesn’t open.

but when I open index.html by double clicking it, it opens the webpage I designed.

This is how my directory looks like
the public folder has 2 files, sketch.js, and index.html.