Difference between package-lock and node_modules/.package-lock

Question

What's the purpose of the additional .package-lock.json inside node_modules? It seems to be a subset of package-lock.json.

I assume this has been asked before, but i couldn't find anything in the npm docs, and google still refuses to properly search for punctuation symbols, so here we are.

PS: It's recreated by npm i, when i delete it. However i cannot find it on older projects of mine, so it appears to be a newer thing.

Answer 1

The additional node_modules/.package-lock.json is a helper file, which speeds up npm under normal circumstances. When npm finds, that node_modules hasn't changed (checked by e.g. looking at the modified-time of package folders), it can be used instead of processing the folder repeatedly.

As RobC mentions in his comment:

A comprehensive description for node_modules/.package-lock.json can be found in the Hidden Lockfiles section of the "yet to be published docs" in the GitHub repo.