Behavioral Design Patterns in JavaScript

In this section

• Strategy Pattern with Dynamic Functions in JavaScript
  Implement runtime algorithm selection in JavaScript with interchangeable functions, classes, and composition boundaries.
• Observer Pattern Using JavaScript Events
  Implement observer flows with browser events, custom events, Node.js EventEmitter, unsubscribe paths, and backpressure limits.
• Command Pattern with Function Queues in JavaScript
  Encapsulate JavaScript actions as commands for queuing, batching, undo/redo behavior, retries, and macro operations.
• Iterator Pattern with JavaScript Generators
  Use generators and iterable protocols to traverse JavaScript collections without exposing their internal representation.
• Template Method Pattern with JavaScript Inheritance
  Define JavaScript algorithm skeletons with base classes, overridable steps, hooks, and inheritance trade-offs.
• Chain of Responsibility Pattern in JavaScript
  Route JavaScript requests through handler chains that can process, transform, pass, short-circuit, or reject work.
• Memento Pattern for State Preservation in JavaScript
  Capture JavaScript object snapshots for undo, rollback, state history, and restoration without leaking internals.
• State Pattern with JavaScript Classes and Objects
  Model state-specific JavaScript behavior with classes, plain objects, transition rules, and explicit state boundaries.
• Visitor Pattern with Double Dispatch in JavaScript
  Add operations to JavaScript object structures with visitor dispatch while weighing indirection, type checks, and extensibility.
• Interpreter Pattern for Parsing Expressions in JavaScript
  Build JavaScript expression interpreters with grammar rules, parse trees, evaluators, and performance limits in mind.
• Mediator Pattern Using Pub/Sub in JavaScript
  Coordinate JavaScript components through pub/sub mediators while controlling coupling, event contracts, and lifecycle cleanup.
• Null Object Pattern with Default Behaviors in JavaScript
  Replace JavaScript null checks with safe default objects while keeping absence, errors, and fallback behavior explicit.
• Command Pattern in Redux and Flux for JavaScript
  Model JavaScript UI state changes as dispatched actions, reducers, command logs, and predictable unidirectional flows.
• Asynchronous Patterns and Promise Chaining in JavaScript
  Compose JavaScript promise chains for sequencing, branching, retries, cleanup, and readable asynchronous workflows.
• Scheduler Pattern in JavaScript Event Loops
  Coordinate JavaScript task timing with event-loop queues, priorities, yielding, timers, and responsiveness trade-offs.
• Service Locator Pattern in JavaScript
  Centralize JavaScript service lookup while understanding hidden dependencies, test friction, lifecycle, and dependency injection alternatives.
• Blackboard Pattern for Collaborative JavaScript Systems
  Use a shared JavaScript knowledge space to coordinate independent workers, rules, hypotheses, and collaborative problem solving.
• Centralized Error Handling Patterns in JavaScript
  Standardize JavaScript error handling with middleware, higher-order wrappers, async boundaries, logging, and recovery policies.
• Implementing Error Boundaries in React
  Implement React error boundaries to catch render failures, show fallback UI, report errors, and define recovery behavior.