React 18 Automatic Batching Patterns Reference for diagnosing and fixing the most dangerous silent breaking change in React 18 for class-component codebases. The Core Change | Location of setState | React 17 | React 18 | |---|---|---| | React event handler | Batched | Batched (same) | | setTimeout | Immediate re-render | Batched | | Promise .then() / .catch() | Immediate re-render | Batched | | async/await | Immediate re-render | Batched | | Native addEventListener callback | Immediate re-render | Batched | Batched means: all setState calls within that execution context flush together in a si…