lean-state-machine

A minimal non-directional state machine, inspired by xstate.

• [x] Transition from any state to any other.
• [x] Minimal footprint - 1/2kb gzipped.
• [x] Extensible via plugins
• [x] Individual files
• [x] Same arguments shape as xstate so you leverage its visualizer
• [x] Zero dependencies

Consider this project as xstate on a low carb, low fat, low protein diet. You only have your essential vitamins and minerals - take some data, associate it with a state. You can extend this state machine with your own features by writing plugins.

yarn add lean-state-machine
# OR
npm install lean-state-machine

Usage

import createMachine from '../src/createMachine';

const params = {
  context: {result: 10, error: undefined},
  initial: 'init',
  states: {
    init: {},
    loading: {},
    success: {},
    error: {},
  }
};

const machine = createMachine(params);
machine.getState();
/*
{
  value: 'init',
  context: {result: 10, error: undefined}
}
*/
machine.context
/* {result: 10, error: undefined} */

newState = machine.update("loading");
newState.value;
/* loading */
newState.context;
/* {result: 10, error: undefined} */

newState = machine.update("success", (context) => ({result: 200}));
newState.value
/* success */
newState.context;
/* {result: 200, error: undefined} */

Why

Xstate is great. And I learnt a lot by studying its documentation. On my projects, I realized I didnt necessarily need the strict enforcement from one state to another specific state. For example. In xstate, you need to define all the possible transitions beforehand. Lets say loading, success, error are states of my system. I would usually define loading->success and loading->failure. But sometimes, i just want to jump from success->failure without having to go throughh loading. Its tedious to have to define all the possible state transitions from one state to another. If you need a strict rule, use xstate. If not, this library works just as well for a minimal use case - data associated with a state. Many front end projects already use a different state management tool like redux/mobs etc. This library gives you the most bang for your buck in terms of being a state machine.

You can pretty much write a plugin to make this library work just like xstate, but at that point, you should probably just use xstate.

Plugins

Docs Coming soon. In the meanwhile, look at src/createExposedMachine.

LICENSE

MIT