Taskcluster's libraries show a great deal more variety than the microservices. They are designed specifically for use in our own services, but still provide a well-documented, understandable API.
Libraries should have simple names and be located in libraries/ in this repository.
Each library should have its own package.json, with its name property set to taskcluster-lib-<simpleName>.
Dependencies should be listed in this package.json, with dev dependencies listed in the package.json in the repository root.
The README.md file should document the library's API completely, without relying on reference to the source.
This file will automatically be linked from the README.md in the root of the repository, via yarn generate.
Library source code should be in a src subdirectory.
No transpilation should be used: write JS that can be interpreted directly by the Node version in use in the repository.
The main property in package.json should point to src/index.js, which may then load other parts of the library.