CS-OA cs-vo Faang

WEB前端面经,react,OA代做

多说web 前端的东西

serialize techer’s writing to make sure that the student don’t see the action out of order

modified lower order network logic for consistent order of teacher’s action

so student are able to understand easily

说说scalabiltiy, 有多少学生用, 然后如何improve user interface让变得更user friendly

useState: Allows you to add state to functional components. It returns the current state value and a function to update it.

  • for example used for form input, use a state variable to record the input value
  • or any other variable values that changes in the program

useEffect: Replaces lifecycle methods like componentDidMount, componentDidUpdate, and componentWillUnmount. It lets you perform side effects in function components.

useContext: Provides a way to consume the context in a component without using a Consumer or wrapping the component in a Provider.

  • Context in React allows you to share data between components without the need to pass props down through all levels of the component tree. It's particularly useful when you have data that many components need to access, like a theme, user authentication, or language preference.

Custom hooks allow you to encapsulate complex logic into a reusable piece of code that can be shared across different components.

  • if a certain logic is repeated multiple times
  • you can create a custom hook to encapsulate the repeated logic

I used redux for state management

What technical stacks the teams is using

What kind of migration is needed? is the old platform incapable of supporting more users?

While universal applications offer numerous benefits, they also come with some challenges and potential pitfalls that developers need to be aware of:

  1. Complexity: Building and maintaining a universal application can be more complex than building a traditional single-page application (SPA). It requires understanding both server-side and client-side rendering, managing data flow between the two, and handling potential issues that arise from dual environments.
  2. Server Load: Server-side rendering (SSR) can put a significant load on the server, especially during high traffic periods. This might require additional server resources to ensure optimal performance and responsiveness.
  3. Build Time: Setting up a universal application often involves additional configuration and build steps to handle server-side rendering and client-side hydration. This can make the development and deployment process more complex and time-consuming.
  4. JavaScript Dependency: Even though universal applications improve initial load performance, they still rely on JavaScript for interactivity after the initial render. If JavaScript fails to load or encounters errors, the user experience might suffer.
  5. Caching Challenges: Caching becomes more complex in universal applications. You need to manage caching strategies for both the server-rendered content and the client-side code to ensure accurate and up-to-date content.
  6. Client-Side Routing: Handling client-side routing in a universal application can be tricky. You need to ensure that routes match both on the server and the client to avoid navigation issues.
  7. Third-Party Libraries: Some third-party libraries might not be compatible with server-side rendering, leading to compatibility issues and potential workarounds.
  8. Data Fetching: Managing data fetching in a universal application requires careful consideration. You need to determine when and how to fetch data on the server and client, ensuring a smooth transition between the two.
  9. Debugging Complexity: Debugging a universal application can be more challenging, as you need to consider both server-side and client-side code. It might require specialized tools and approaches to trace issues effectively.
  10. SEO Implications: While universal applications generally improve SEO, improper implementation or dynamic client-side updates can still impact SEO. Ensuring that search engines correctly index your content requires attention to detail.
  11. Learning Curve: Developers who are new to server-side rendering might face a learning curve when adopting universal applications. It requires understanding the nuances of both client-side and server-side JavaScript execution.

A "universal application," also commonly referred to as an "isomorphic application," is a term used in the context of web development to describe an application that can run both on the server side and the client side, using the same codebase. The goal of a universal application is to provide a seamless user experience, improve performance, and enhance search engine optimization (SEO).In a universal application:

  1. Server-Side Rendering (SSR): When a user requests a page, the server generates the HTML content with the appropriate data and sends it to the client. This means that the initial rendering of the application occurs on the server, resulting in faster page loads and improved SEO, as search engines can better index the content.
  2. Client-Side Interaction: After the initial HTML is sent to the client, the application "hydrates" itself by attaching event listeners and JavaScript functionality. Subsequent interactions and updates are handled on the client side, making the application dynamic and interactive.
  3. Shared Code: A key aspect of universal applications is the ability to reuse the same codebase for both server and client. This code sharing reduces duplication, simplifies maintenance, and ensures consistency between the two environments.
  4. Enhanced SEO: Traditional single-page applications (SPAs) often face challenges with SEO because search engines might not effectively index content loaded via JavaScript. With universal applications, the initial HTML content is rendered on the server, which is easily indexable by search engines.

Frameworks like Next.js (for React applications) and Nuxt.js (for Vue.js applications) simplify the process of building universal applications by providing tools and conventions for handling server-side rendering, routing, and data fetching. However, building a universal application requires careful consideration of various factors, such as data fetching strategies, routing patterns, and SEO practices, to ensure optimal performance and user experience.

Redux is used when the website have many data to store

Redux is particularly useful in certain scenarios where your application's state management becomes complex and needs to be predictable and manageable. Here are some situations where using Redux might be beneficial:

The principles of Redux are a set of concepts and guidelines that define how the Redux library operates and how it should be used to manage state in your application. These principles ensure a predictable and manageable way of handling application state. The key principles of Redux are:

  1. Single Source of Truth: In Redux, all application state is stored in a single JavaScript object known as the "store." This ensures that there's only one place to look for the current state of your application, making it easier to understand and maintain.
  2. State is Read-Only: The state in a Redux application is immutable, which means it cannot be directly modified. Instead of modifying the state, you create new state objects by dispatching actions. This promotes predictability and helps prevent unexpected side effects.
  3. Changes are Made with Pure Functions (Reducers): To update the state, you define pure functions called "reducers." These reducers take the current state and an action as input and return a new state. Reducers are predictable and ensure that the state changes are traceable and deterministic.
  4. Changes are Described with Actions: Actions are plain JavaScript objects that describe the intention to change the state. They typically have a type property that describes the type of action and any additional data required for the change. Actions are dispatched to the store to trigger state updates.

It seems like you're looking for state management tools or libraries that are commonly used in web applications to handle complex state management. Here are some popular options:

  1. Redux: Redux is a widely used state management library for JavaScript applications, particularly with React. It follows a unidirectional data flow pattern and emphasizes a single source of truth for application state.
  2. Mobx: Mobx is another state management library that focuses on making state management simple and scalable. It uses observables and reacts to changes automatically, which can reduce boilerplate code.
  3. Vuex: Vuex is the state management library for Vue.js applications. It provides a centralized store for all the components and helps manage complex state in Vue applications.
  4. NgRx: NgRx is a state management library for Angular applications. It's inspired by Redux and follows the principles of unidirectional data flow, actions, and reducers.
  5. Apollo Client: If your application involves GraphQL, Apollo Client is a popular choice for state management. It integrates well with GraphQL APIs and provides caching and state management capabilities.

Redux is a state management library for JavaScript applications, particularly those built with libraries like React. It offers a centralized way to manage and share the state of an application across different components, making it easier to maintain, debug, and scale large and complex applications. Here are some reasons why you might use Redux:

  1. Centralized State Management: Redux provides a single source of truth for the state of your application. Instead of scattering state across various components, all state is stored in a central store. This makes it easier to understand how data changes and simplifies debugging.
  2. Predictable State Updates: In Redux, state changes are made through pure functions called reducers. This ensures that state changes are predictable and easy to trace, as each state transition is explicitly defined.
  3. Component Decoupling: Redux helps decouple components from the need to manage state. Components can focus on rendering and user interactions, while the state management logic is handled by Redux. This separation leads to more reusable and maintainable code.

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