Built on familiar standards such as SystemJS and WebPack, the loader is the first part of the SharePoint Framework to load on a page. It manages versioning and loading of client-side components, web parts, and other assets. It also provides basic diagnostic services.
This package is part of the SharePoint Framework, which is a collection of NPM packages that empower developers to create client-side experiences for Microsoft SharePoint. For more information, including complete API documentation and code samples, please visit the SharePoint Framework web site.