xstate@6.0.0-beta.0

Minor Changes

• 81dd3dd: Restoring a persisted snapshot moved out of createActor into restoreActor, exported from the new xstate/persist entry point. createActor only starts fresh actors; passing snapshot throws with the replacement.

  // Before
  const actor = createActor(machine, { snapshot: persisted });
  
  // After
  import { restoreActor } from 'xstate/persist';
  
  const actor = restoreActor(machine, persisted);

  restoreActor(logic, snapshot, options?) works for any actor logic and accepts the createActor options except input. Pass system to restore into a system from createSystem():

  const actor = restoreActor(machine, persisted, { system });

  Machine snapshots are validated and migrated, and invoked and spawned children are restored. A snapshot that cannot be restored produces an actor with an 'error' snapshot. machine.restoreSnapshot() is removed.

  machine.snapshotSchema and machine.eventSchema are now functions:

  // Before
  await machine.snapshotSchema['~standard'].validate(value);
  await machine.eventSchema['~standard'].validate(input);
  
  // After
  import { eventSchema } from 'xstate';
  import { snapshotSchema } from 'xstate/persist';
  
  await snapshotSchema(machine)['~standard'].validate(value);
  await eventSchema(machine)['~standard'].validate(input);

  machineVersions([...]) accepts machines and { id, version, snapshotSchema, eventSchema } descriptors as before.

• 047cfb5: Leftover v5 configuration now throws in every build instead of only in development, so it cannot be silently ignored:

  • createMachine(config, implementations) and setup(...).createMachine(config, implementations) throw. Declare implementations in setup({ ... }) or pass them to machine.provide({ ... }).
  • services, activities and devTools in a machine config throw. They previously only warned in development.
  • createActor(...) throws on an option it does not read. Removed options (systemId, state, devTools, parent, deferEvents, execute) throw with their replacement; any other unknown option throws with the list of supported options.

  createActor(machine, { systemId: 'payments' });
  // Error: The "systemId" actor option was renamed. Use "registryKey": createActor(logic, { registryKey }), and look the actor up with system.get(registryKey).

  predictableActionArguments, preserveActionOrder and strict change nothing in v6 and still only warn in development.

• 965c250: Macrosteps are unbounded by default, as in v5. options.maxIterations no longer defaults to 1000, so a machine whose eventless transitions or raised events take more than 1000 microsteps for one event keeps running instead of erroring. In development builds, a macrostep that passes 1000 microsteps logs a warning once per machine. Set maxIterations to turn a runaway macrostep into an InfiniteTransitionError:

  const machine = createMachine({
    options: { maxIterations: 5000 },
    // ...
  });

Patch Changes

• 6cf6982: XState v6 enters beta. No further breaking changes are planned for APIs tagged @public; any that are needed will be called out with a migration path. APIs tagged @experimental may still change.

• 308c52d: self in actions, transition functions, context factories, input mappers and delay functions is typed as a machine actor ref instead of any in its children and meta positions. Delay and after functions now receive the machine's emitted event type.

• a2e4161: Production builds report errors and diagnostics as short codes. Each message names the code, the values that identify the failing state, event, or actor, and a link to its entry in the error code reference:

  XState error E1 ("services"). See https://github.com/statelyai/xstate/blob/next/docs/errors.md#e1
  

  Development messages are unchanged. Error classes and names are the same in both builds.

• 59fc7cd: createMachine throws when an on key is a v5 suffixed lifecycle event type such as 'xstate.done.actor.job', 'xstate.error.actor.job', 'xstate.done.state.form' or 'xstate.after.1000.loading'. v6 never sends these types, so the transition never fired. The error names the replacement:

  // Throws: Transition "xstate.done.actor.job" in state "loading" never fires ...
  on: { 'xstate.done.actor.job': { target: 'done' } }
  
  // Use the category type and select the child with `matches`
  on: { 'xstate.done.actor': { matches: { actorId: 'job' }, target: 'done' } }

  Wildcards such as 'xstate.done.actor.*' and the 'xstate.snapshot.actor' type are unaffected.