State Management Antipatterns

Overview

State management antipatterns occur when application state is handled in ways that make code unpredictable, hard to debug, and impossible to test.

Common Problems

1. Global Mutable State

Shared variables that any part of the code can modify.

2. Feature Flag Chaos

Conflicting, stale, or poorly managed feature flags.

3. Hidden Dependencies

State accessed through globals instead of explicit parameters.

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Articles in This Section

• Global Mutable State - Shared state chaos
• Feature Flags - Flag management gone wrong

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Quick Comparison

Antipattern	Problem	Solution
Global Mutable State	Unpredictable changes	Dependency injection
Feature Flags Chaos	Conflicting conditions	Feature flag service

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Key Principles

1. Explicit is Better Than Implicit

// Bad - hidden dependency
function getDiscount() {
  return globalConfig.discountRate * globalUser.tier
}

// Good - explicit parameters
function getDiscount(config, user) {
  return config.discountRate * user.tier
}

2. Immutable When Possible

// Bad - mutating state
globalState.users.push(newUser)

// Good - create new state
const newState = {
  ...state,
  users: [...state.users, newUser]
}

3. Single Source of Truth

// Bad - state scattered everywhere
const userCache = {}  // in cache.js
const userData = {}   // in user.js
const userSession = {} // in session.js

// Good - centralized store
const store = createStore({
  users: {},
  sessions: {},
  cache: {}
})