To optimize performance, AngularJS controllers should handle events using Observables instead of traditional JavaScript methods. Observables provide a powerful and efficient way to handle asynchronous events, making it easier to manage and react to changes in the application. This is a key concept in AngularJS that enhances the overall responsiveness and performance of the application.

In AngularJS, $watch is used to watch for changes in scope variables and update the view accordingly. It allows developers to track changes in model data and trigger the necessary updates in the UI. Understanding how to use $watch is crucial for building dynamic and responsive AngularJS applications.

Handling API rate limits is crucial in scenarios where an AngularJS application makes frequent requests to an API. Implementing mechanisms such as client-side caching, request throttling, and error handling can help manage and respect API rate limits. This ensures that the application operates within the allowed usage thresholds, preventing service disruptions and enhancing overall reliability.

AngularJS handles the conditional display of elements in the view through the ng-show and ng-hide directives. These directives allow developers to conditionally show or hide elements based on expressions evaluated in the AngularJS scope. This declarative approach simplifies the management of conditional logic in the view, promoting a more maintainable and expressive codebase. Understanding how AngularJS handles conditional display is crucial for creating dynamic and responsive user interfaces.

In AngularJS, scope broadcasting is done using the $broadcast method. This method allows the child scopes to emit events to their parent scopes. By using $broadcast, developers can communicate between different parts of the application and synchronize data updates. Mastering the use of $broadcast is essential for effective communication in AngularJS applications.

The ng-repeat directive is essential for rendering lists or tables dynamically in AngularJS. It iterates over a collection of items and generates HTML elements for each item. This powerful directive is commonly used to display data from arrays or objects, making it a key feature for building dynamic and responsive user interfaces in AngularJS applications.

The ng-class directive in AngularJS allows you to dynamically manipulate CSS classes on an HTML element based on the data in the scope. It is commonly used for conditional styling, where the presence or absence of a class depends on certain conditions. Understanding how to use ng-class is crucial for creating dynamic and responsive user interfaces in AngularJS applications.

The ng-switch directive in AngularJS enhances decision-making capabilities in the view by dynamically switching between different views based on the provided conditions. It acts as a more expressive and efficient alternative to using multiple if-else conditions in the view. With ng-switch, the view can adapt and display different content based on the evaluated expressions, providing a cleaner and more readable way to handle complex conditional rendering in AngularJS applications.

AngularJS optimizes DOM manipulation using directives like ng-show and ng-if by employing Virtual DOM manipulation. Instead of directly manipulating the actual DOM, AngularJS creates a virtual representation of the DOM in memory. Changes are made to this virtual DOM, and then AngularJS efficiently updates the actual DOM based on the differences. This minimizes the number of DOM manipulations, leading to better performance in AngularJS applications.

In AngularJS, errors while making HTTP requests to an external API can be handled using error callback functions. When working with promises, developers can attach an error callback to handle any errors that occur during the HTTP request. This ensures a graceful handling of errors and provides an opportunity to notify users or take appropriate actions based on the error type. Understanding how to handle errors in asynchronous operations is a critical skill for AngularJS developers working with external APIs.

Modules are a key AngularJS concept that helps in preventing scope conflicts in large applications. Modules provide a way to organize and structure an AngularJS application by encapsulating related components. They help in managing dependencies, defining reusable code, and enhancing modularity. Understanding how to use modules is fundamental for building scalable and maintainable AngularJS applications.

In advanced AngularJS applications, "controller-as" syntax is used for controller aliasing to enhance readability. It allows you to avoid scope-related issues and makes it clear which controller is associated with a particular section of the view. The "controller-as" syntax is considered a best practice for maintaining clean and readable code in AngularJS.