R
fn

createMachine

tested

Create a type-safe synchronous finite state machine with context

Source Tests

Example

ts
const machine = createMachine({
  initial: 'idle',
  context: { retries: 0 },
  states: {
    idle: {
      on: { START: 'running' },
    },
    running: {
      on: {
        FAIL: {
          target: 'idle',
          guard: (ctx) => ctx.retries < 3,
          action: (ctx) => { ctx.retries++; },
        },
        STOP: 'idle',
      },
    },
  },
});

machine.send('START'); // 'running'

Signatures

ts
export function createMachine<
  const States extends Record<string, SyncStateNodeConfig<Context>>,
  Context,
>(config: {
  initial: NoInfer<ExtractStates<States>>;
  context: Context;
  states: States;
}): StateMachine<ExtractStates<States>, ExtractEvents<States>, Context>;
ts
export function createMachine<
  const States extends Record<string, SyncStateNodeConfig<undefined>>,
>(config: {
  initial: NoInfer<ExtractStates<States>>;
  states: States;
}): StateMachine<ExtractStates<States>, ExtractEvents<States>, undefined>;

Parameters

ParameterTypeDescription
config{ initial: string; context?: unknown; states: Record<string, SyncStateNodeConfig<any>>; }—

Returns

StateMachine<string, string, undefined>