I’ve had some students of my bootcamp run into this problem I never noticed.

It’s due to the behavior of npm when installing a package in an empty folder.

I was suggesting to use npm install <packagename, for example in this way:

npm install my-prime


in an empty folder.

By default this creates a package.json with the package as a dependency, a package-lock.json and installs the package in node_modules.

But some people were not seeing this happen. Nothing seemed to happen.

What happened however is that they had a package.json file and a node_modules folder up in the directory tree.

Maybe not even in the parent folder, but higher in the hierarchy.

Maybe they ran npm install <package> in their home folder without realizing, probably for a test.

npm will walk up the folder tree checking for a folder that contains either a package.json file, or a node_modules folder. If such a thing is found, then that is treated as the effective “current directory” for the purpose of running npm commands.

Source

To fix this problem, the best solution is to remove the parent package.json and node_modules.

It’s probably there by mistake.

Otherwise you could also run npm init -y in the folder to create a blank package.json file, then re-run the npm install <package> command, which will now work as expected.