XState

Overview

XState models application logic as state machines. Instead of managing boolean flags (isLoading, isError, isSuccess), you define states and transitions explicitly — making impossible states impossible. Ideal for complex flows: checkout, onboarding, authentication, multi-step forms.

Instructions

Step 1: Define a Machine

// machines/authMachine.ts — Authentication state machine
import { setup, assign, fromPromise } from 'xstate'

export const authMachine = setup({
  types: {
    context: {} as {
      user: { id: string; name: string; email: string } | null
      error: string | null