statelyai/xstate xstate@4.23.0

on GitHub

Minor Changes

• 7dc7ceb8 #2379 Thanks @davidkpiano! - There is a new .preserveActionOrder (default: false) setting in the machine configuration that preserves the order of actions when set to true. Normally, actions are executed in order except for assign(...) actions, which are prioritized and executed first. When .preserveActionOrder is set to true, assign(...) actions will not be prioritized, and will instead run in order. As a result, actions will capture the intermediate context values instead of the resulting context value from all assign(...) actions.

  // With `.preserveActionOrder: true`
  const machine = createMachine({
    context: { count: 0 },
    entry: [
      ctx => console.log(ctx.count), // 0
      assign({ count: ctx => ctx.count + 1 }),
      ctx => console.log(ctx.count), // 1
      assign({ count: ctx => ctx.count + 1 }),
      ctx => console.log(ctx.count) // 2
    ],
    preserveActionOrder: true
  });
  
  // With `.preserveActionOrder: false` (default)
  const machine = createMachine({
    context: { count: 0 },
    entry: [
      ctx => console.log(ctx.count), // 2
      assign({ count: ctx => ctx.count + 1 }),
      ctx => console.log(ctx.count), // 2
      assign({ count: ctx => ctx.count + 1 }),
      ctx => console.log(ctx.count) // 2
    ]
    // preserveActionOrder: false
  });

Patch Changes

• 4e305372 #2361 Thanks @woutermont! - Add type for Symbol.observable to the Interpreter to improve the compatibility with RxJS.

• 1def6cf6 #2374 Thanks @davidkpiano! - Existing actors can now be identified in spawn(...) calls by providing an id. This allows them to be referenced by string:

  const machine = createMachine({
    context: () => ({
      someRef: spawn(someExistingRef, 'something')
    }),
    on: {
      SOME_EVENT: {
        actions: send('AN_EVENT', { to: 'something' })
      }
    }
  });

• da6861e3 #2391 Thanks @davidkpiano! - There are two new helper types for extracting context and event types:

  • ContextFrom<T> which extracts the context from any type that uses context
  • EventFrom<T> which extracts the event type (which extends EventObject) from any type which uses events