Controllers and scopes create hierarchies in web frameworks, enabling data flow and communication between components. They organize complex applications, allowing parent-child relationships and efficient data sharing for responsive interfaces.

Advanced AngularJS directives create reusable components with isolated scope and transclusion. They use controllers for logic, can require other directives, and allow complex functionality like custom dropdowns.

Services and dependency injection patterns enhance code reusability and modularity. They enable easier testing, maintenance, and flexibility in application development. Singleton services ensure consistent state across the app.

Custom AngularJS filters transform data in views, enhancing code reusability. They can manipulate text, truncate strings, filter items, and sort arrays. Performance considerations are crucial when creating complex filters.

AngularJS component-based architecture promotes reusability, modularity, and easier maintenance. It simplifies development by creating self-contained UI elements with isolated scopes, improving testability and aligning with modern web practices.

Custom form validation ensures data integrity and user-friendliness. Directives extend HTML with custom behavior, allowing for reusable validation logic. Meaningful feedback and server-side checks enhance user experience.

ngMessages simplifies Angular form validation, offering cleaner templates and reusable error messages. It handles various validation states, supports custom validators, and improves user experience with clear, context-specific feedback.

Promises and $q in AngularJS simplify async operations, avoiding callback hell. They enable chaining, parallel execution, and easy error handling. Promises represent future values, making code cleaner and more maintainable.

AngularJS's $http and $resource simplify RESTful API interactions. $http handles basic HTTP requests, while $resource provides higher-level abstractions for CRUD operations. Both support promises for asynchronous handling.

AngularJS interceptors: global HTTP request/response handlers. Useful for authentication, error management, and logging. Four types available. Implement as factories, add to $httpProvider.interceptors. Powerful but use judiciously.

AngularJS caching with $cacheFactory boosts performance by storing data locally. It reduces server requests, improves speed, and enhances user experience. Careful implementation is key for optimal results.

ui-router introduces states for complex app structures. It offers nested states, multiple views, state parameters, and resolve functions. Mastering ui-router enhances single-page application development, enabling organized and efficient routing configurations.

Route resolvers load crucial data before page rendering, enhancing user experience. They prevent blank pages, handle authentication, and ensure smooth navigation. Use sparingly for essential data and combine with loading indicators.

AngularJS state management: Use services for data sharing, event handling for updates, and centralized stores for complex apps. Normalize data, create computed properties, and maintain consistency across the application.

WebSockets enable real-time, two-way communication in AngularJS apps. They allow instant data updates without polling, ideal for chat, collaboration tools, and live dashboards. Implement securely using WSS and proper authentication.

AngularJS testing with Jasmine and Karma ensures robust apps. Set up environment, test controllers, services, and directives. Write testable code, use debug mode, and explore advanced tools for comprehensive testing.

Protractor enables end-to-end testing for AngularJS apps, simulating user interactions. It integrates with Selenium, uses Jasmine framework, and supports asynchronous operations. Page objects enhance test readability and maintainability.

AngularJS performance optimization: Minimize watchers, use one-time bindings, implement lazy loading, utilize track by in ng-repeat, debounce rapid events, leverage ng-if, and employ Web Workers for heavy processing.

AngularJS debugging tools like Batarang and Augury help inspect scopes, performance, and dependencies. Common issues include scope problems, performance bottlenecks, and dependency injection errors. Breakpoints and console.log are useful debugging techniques.

A blog app using React, Redux, and styled-components. Features include routing, form validation, state management, and markdown support. Create, view, and style posts easily.