ADR010: Use the Luxon Date Library

Context

Date formatting (e.g. a day ago) and calculations are common within Backstage. Some of these useful features are not supported by the standard JavaScript Date object. The popular Moment.js library has been commonly used to fill this gap but is affected by large bundle sizes and mutable state issues. On top of this, momentjs is being sunset and the project recommends using one of the more modern alternative libraries.

See [RFC] Standardized Date & Time Library.

Decision

We will use Luxon as the standard date library within Backstage.

Luxon provides a similar feature set and API to Moment.js, but improves on its design through immutability and the usage of modern JavaScript APIs (e.g. Intl). This results in smaller bundle sizes while providing a full feature set and avoids the need for using additional libraries for common date & time tasks.

Consequences

• All core packages and plugins within Backstage should use Luxon for any date manipulation or formatting that cannot be easily accomplished with the native JavaScript Date object.
• Using a single date library avoids having to learn multiple library APIs
• Having a single date library will reduce bundle sizes