XState v6 alpha
TypeScript
Define schemas and derive XState types.
Define runtime schemas with setup(...). XState infers context, events, input and output from them.
Enable TypeScript's strict mode. Keep schemas next to actor logic so runtime validation and inferred types describe the same contract.
import { z } from 'zod';
import { setup } from 'xstate';
const machine = setup({
schemas: {
context: z.object({ count: z.number() }),
events: {
increment: z.object({})
},
input: z.object({ initialCount: z.number() })
}
}).createMachine({
context: ({ input }) => ({ count: input.initialCount }),
initial: 'active',
states: { active: {} }
});Schema event keys also create typed methods on actor.trigger.
actor.trigger.increment();Event types narrow inside transitions:
on: {
search: ({ event }) => {
event.query; // string
}
}Use assertEvent(...) only when shared code must narrow a union to one or more known event types.
Type helpers
| Helper | Derives |
|---|---|
ActorRefFrom<T> | Actor reference type. |
SnapshotFrom<T> | Snapshot type. |
EventFromLogic<T> | Accepted event type. |
InputFrom<T> | Input type. |
OutputFrom<T> | Final output type. |
TypeScript cheatsheet
type Actor = ActorRefFrom<typeof machine>;
type Snapshot = SnapshotFrom<typeof machine>;
type Event = EventFromLogic<typeof machine>;
type Input = InputFrom<typeof machine>;
type Output = OutputFrom<typeof machine>;