state-shifter

state-shifter

Simple TypeScript state manager for workflows that behave like a finite state machine.

Installation

npm install state-shifter

Usage

import { StateShifter, type StateShifterConfig } from "state-shifter";

type AppState = "idle" | "loading" | "ready" | "error";

type AppMachine = StateShifterConfig<
  Record<AppState, readonly AppState[]>,
  (event: string) => void
>;

const transitionGraph = {
  idle: ["loading"],
  loading: ["ready", "error"],
  ready: ["loading"],
  error: ["loading"],
} as const;

const shifter = new StateShifter<AppMachine>("idle", transitionGraph, {
  idle: {
    onEnter: () => console.log("Idle"),
  },
  loading: {
    onEnter: () => {
      console.log("Loading...");
      setTimeout(() => {
        void shifter.shiftTo("ready");
      }, 2000);
    },
  },
  ready: {
    onEnter: () => console.log("Ready"),
  },
}, false);

await shifter.start();
await shifter.shiftTo("loading");

API

• new StateShifter(initialState, transitionGraph, behaviors, implicitStart?)
• start()
• getCurrentState()
• dispatchEvent(...args)
• canShift(from, to)
• shiftTo(to, params?)

License

MIT