statelyai/xstate xstate@4.24.0

on GitHub

Minor Changes

• #2546 a4cfce18c Thanks @davidkpiano! - You can now know if an event will cause a state change by using the new state.can(event) method, which will return true if an interpreted machine will "change" the state when sent the event, or false otherwise:

  const machine = createMachine({
    initial: 'inactive',
    states: {
      inactive: {
        on: {
          TOGGLE: 'active'
        }
      },
      active: {
        on: {
          DO_SOMETHING: { actions: ['something'] }
        }
      }
    }
  });
  
  const state = machine.initialState;
  
  state.can('TOGGLE'); // true
  state.can('DO_SOMETHING'); // false
  
  // Also takes in full event objects:
  state.can({
    type: 'DO_SOMETHING',
    data: 42
  }); // false

  A state is considered "changed" if any of the following are true:

  • its state.value changes
  • there are new state.actions to be executed
  • its state.context changes

  See state.changed (documentation) for more details.

Patch Changes

• #2632 f8cf5dfe0 Thanks @davidkpiano! - A regression was fixed where actions were being typed as never if events were specified in createModel(...) but not actions:

  const model = createModel(
    {},
    {
      events: {}
    }
  );
  
  model.createMachine({
    // These actions will cause TS to not compile
    entry: 'someAction',
    exit: { type: 'someObjectAction' }
  });