This article talks about package manager in Javascript.
They are the first component of the web toolchain as they permit to:
The Javascript ecosystem is based on the npm specification and relies on the package.json file as manifest to describe a package. Therefore every time, you see a package.json in a directory, this is the root directory of package
A non-exhaustive list of package manager
They have all their own implementation of node_modules directory that should contain all Javascript dependency
Create a directory by package manager and add a dependency to see the difference
pnpm add express
npm add express
pnpm add express
Every package manager creates a shrinkwrap file that should be committed in your version repository.
You can define it with the packageManager property in package.json