However, if SystemJS can import modules from any sources, how does it know where to find the modules? For instance, if we do SystemJS.import('moment'), should SystemJS fetch the package from the NPM registry? Or is it a custom repository? SystemJS can't know for sure. Therefore, to use SystemJS efficiently, we must use a package manager that can maintain a mapping between package names and their location. Luckily for us, there is jspm, which stands for JavaScript Package Manager.
jspm is similar to npm and yarn, but it can download modules/packages from anywhere, not just from npm. Furthermore, it will automatically create a SystemJS configuration file with all the package-to-location mapping we talked about previously.
