React 18 improves the existing behavior of Suspense

React 18 delays committing everything inside the Suspense boundary (the suspended component and all its siblings) until the suspended data resolves.

Rails 7 allows setting cache expiry, as an absolute timestamp

With the introduction of expires_at to Rails Cache it is now possible to set absolute timestamps for cache expiry.

Rails 7 adds change tracking methods for belongs_to associations

Rails 7 adds the ability to track if an association has been pointed to a new target record in the previous save and whether it will point to a new target record in the next save.

React 18 adds automatic batching

React 18 adds out-of-the-box performance improvements by doing more batching by default.

Rails 7 allows loading nested locales in the engine

Rails 7 allows loading nested locales inside the `/locales` directory by default for better organization in larger apps.

React 18 introduces new root API ( ReactDOM.createRoot )

React 18 adds the new root API that comes up with the new out-of-the-box improvements.

Rails 7 adds support for `if_exists/if_not_exists` on `remove_foreign_key/add_foreign_key`

Rails 7 adds support for `if_exists/if_not_exists` on `remove_foreign_key/add_foreign_key` in migrations to silently ignore raised exceptions.

Rails 7 MySQL adapter improves the security of untyped bound values

MySQL adapter in Rails 7 casts numbers and booleans to string to avoid security vulnerabilities.

React 17 attaches events to the root DOM container instead of the document node

React 17 delegates events to the root node instead of the document node, making it easier to embed React into apps built with other technologies

Ruby 3.1 introduces pattern matching pin operator against expression

Ruby 3.1 adds support for the expression and range when using the pattern matching pin operator.