state-machines-pattern

To prevent impossible states in TypeScript workflows, replace boolean flag combinations with explicit state unions. Modeling application logic as a state machine ensures only valid, deterministic transitions occur, eliminating impossible states caused by ad-hoc if/else chains.

Use a state machine for multi-step async operations when your business process requires defined rules and deterministic transitions. Explicit transition tables, guards, and actions separate decision logic from state definitions, ensuring safe transitions and testable behavior for complex async data-fetch workflows.

Define deterministic transitions and guards by creating explicit transition tables that map valid state changes. Guards and actions separate decision logic from state definitions, while a typed context travels with the machine and updates only through transitions to ensure exhaustive, safe behavior.

Yes, this state machine pattern works for complex business processes and multi-step forms. By defining explicit state unions and transition tables, you can model defined rules and multi-step workflows, preventing illegal states that typically arise from ad-hoc if/else chains.

The best way to model context and extended state is to use a typed context that travels with the machine. This context updates only through explicit transitions, ensuring that extended state remains consistent and safe alongside the defined state unions and transition tables.