Full Stack Interview Questions and Answers- Part 7

Answer:

The debounce function in JavaScript is used to control how often a particular function is executed in response to an event, like scrolling or typing. It prevents the function from being called multiple times rapidly by waiting for a specified time after the last event before invoking the function. This is especially useful to improve performance and responsiveness by reducing unnecessary function calls.

Answer:

In a GraphQL server, error handling can be managed by customizing the error format to provide meaningful information, incorporating error codes for easy identification, and using middleware or higher-order functions to catch errors in resolver functions. This ensures that errors are well-organized and can be effectively dealt with on both the server and client sides.

Answer:

In React, the useMemo hook is used to memoize values, preventing recalculations if the inputs remain the same. The useCallback hook, on the other hand, is used to memoize functions, ensuring that they don’t get recreated on every render unless their dependencies change. These hooks can improve performance by optimizing the re-rendering process.

Answer:

A JavaScript generator-function is a type of function that can be paused and resumed during its execution. It’s defined like a regular function, but it uses the `yield` keyword to produce values one at a time. When a generator-function encounters a `yield` statement, it temporarily suspends execution and yields a value. The generator maintains its state, allowing it to resume from where it left off when requested.

Answer:

A React component undergoes three main phases: mounting, updating, and unmounting. Each phase has associated lifecycle methods that allow you to perform actions at specific points:

• Mounting: constructor, getDerivedStateFromProps, render, componentDidMount.
• Updating: getDerivedStateFromProps, shouldComponentUpdate, render, getSnapshotBeforeUpdate, componentDidUpdate.
• Unmounting: componentWillUnmount.

Answer:

Controlled components have their input values managed by React’s state, using event handlers to update their values. Uncontrolled components, however, rely on the DOM for input state management. Controlled components are preferred when precise control and synchronization with React state are required, while uncontrolled components might be suitable for simpler cases.

Answer:

In Node.js, modules like http or fs use Event objects to emit events that indicate changes, resource availability, or errors. These Event-driven modules follow the observer pattern, allowing applications to respond to events asynchronously. This approach is particularly useful for handling I/O-bound tasks efficiently.

Answer:

In Angular, you can create a custom Pipe by implementing the PipeTransform interface, decorating the class with the @Pipe decorator, and defining the transformation logic. Pipes are used within Angular templates to transform data before rendering it. They can be used to format, filter, or modify data displayed to users.

Answer:

For larger Vue.js applications, Vuex is a recommended state management solution. Vuex provides a centralized store for managing state and offers mechanisms like actions, mutations, and getters to manage state changes predictably and efficiently. This ensures a clear and consistent way to handle state across the entire application.

Answer:

Reactive programming is a programming paradigm that revolves around working with data streams and reacting to changes or events. It enables asynchronous, event-driven programming, which is especially advantageous in web development. Reactive programming can lead to more maintainable code, enhanced responsiveness, and simplified handling of complex asynchronous scenarios, making web applications more efficient and resilient.

Answer:

To enable message passing between a Python web application’s server and a WebSocket client, you can use libraries like Flask-SocketIO or Django Channels. These libraries allow you to create WebSocket connections that facilitate real-time communication through event-based messaging between the server and the client.

Answer:

Handling optimistic updates in a web application involves immediately updating the client-side state and UI to reflect a user action, assuming the server request will succeed. If the server request fails, the previous state is restored, and the user is notified. This approach can be implemented using state management libraries like Redux or Vuex.

Answer:

Error boundaries in React can be implemented by creating a component that defines either the componentDidCatch lifecycle method or the static getDerivedStateFromError method. This component can then wrap around other components in the component tree to catch and handle errors occurring within them.

Answer:

Request blocking occurs when the browser delays rendering while waiting for a resource to be fetched. To address request blocking:

• Use async or defer attributes on script tags.
• Load CSS stylesheets with the media attribute or via JavaScript.
• Minimize custom web fonts or control their loading using font-display.
• Prioritize critical resources and implement lazy-loading for non-critical resources.

Answer:

Atomic design is a design methodology that involves breaking down a user interface into five levels of components: atoms, molecules, organisms, templates, and pages. Each level represents a specific complexity and can be combined to build consistent and modular UIs.

Answer:

To create a performance benchmarking tool for Node.js, utilize built-in modules like perf_hooks or external libraries like Benchmark.js. These tools help measure the runtime of specific code segments, providing insights into performance characteristics.

Answer:

Semantic elements in HTML are tags that provide meaningful structure and context to the content they enclose. These elements communicate the intended purpose of the content to both developers and browsers, making the code more readable and aiding accessibility.

Answer:

In HTML, tags are keywords enclosed in angle brackets, which define the beginning and end of HTML elements. Elements are composed of tags and content and form the building blocks of web pages. Attributes provide additional information about elements and are included within opening tags.

Answer:

JavaScript is a widely-used scripting language for both client-side and server-side programming. It can be included in HTML documents using three methods: embedded coding with the `< script >` tag, internal linking using HTML event attributes, and external linking using the `< script >` tag with the `src` attribute.

Answer:

JavaScript libraries play a crucial role in web development. Some notable libraries are:

• React Js: A JavaScript library for building user interfaces, especially for web applications.
• Express.js: A back-end web application framework for building RESTful APIs with Node.js.
• Next.js: A React framework that offers features like server-side rendering and static site generation.
• Vue.js: A JavaScript framework for building user interfaces and single-page applications with a focus on simplicity and flexibility.