To get list of installed packages in current folder run
npm ls or
npm ls -g to list globally installed packages.
To view only portion of the list, i.e. to display max depth of the dependency tree, there is a useful flag
Whole command looks like this:
npm ls --depth=0 or
npm ls --depth=1 -g
Note: If some packages are not registered in npm registry, there will be marked with “extraneous”