What is the main advantage of "CSS Modules" over regular CSS when working in large teams?

  • Improved performance due to smaller file sizes.
  • Scoped styles that prevent naming conflicts.
  • Built-in support for animations and transitions.
  • Greater compatibility with legacy browsers.
The primary advantage of "CSS Modules" over regular CSS in large teams is scoped styles. CSS Modules ensure that class names are locally scoped to prevent naming conflicts, making it easier to work on individual components without affecting others. While the other options may have benefits, they are not the main advantage of CSS Modules in the context of large team collaboration.

In styled-components, the syntax styled.___ allows you to create a styled component, where "___" is the HTML element name.

  • Component
  • Element
  • Wrapper
  • div
In styled-components, the syntax for creating a styled component uses the name of the HTML element you want to style as a function, for example, styled.div or styled.button. So, in the provided question, "___" should be replaced with "Element," as it represents the HTML element name you intend to style.

In class components, which method is called right before a component is removed from the DOM?

  • componentWillUnmount()
  • componentDidUpdate()
  • componentWillMount()
  • componentWillUnmount()
In class components, the componentWillUnmount() method is called right before a component is removed from the DOM. This is the ideal place to perform cleanup tasks, such as removing event listeners or clearing timers, to prevent memory leaks or unexpected behavior after the component is unmounted. The other options are lifecycle methods, but they serve different purposes.

For an application where state changes are frequent and involve complex logic, which state management solution might be more suitable?

  • Apollo Client.
  • Flux architecture.
  • MobX
  • React's built-in useState hook.
In an application where state changes are frequent and involve complex logic, MobX might be a more suitable state management solution. MobX provides fine-grained reactivity, allowing you to selectively observe and track changes in specific parts of the state. This can lead to more efficient updates and better performance, especially in scenarios with complex state dependencies and updates.

What is the main difference between stateful and stateless components in React?

  • Stateful components can't hold internal data.
  • Stateless components can't render JSX elements.
  • Stateful components use functional components.
  • Stateless components have no lifecycle methods.
The main difference between stateful and stateless components in React is that stateful components can hold and manage internal data (state), whereas stateless components do not hold internal state. Stateful components have a state, which can change over time and trigger re-renders, while stateless components rely solely on the props passed to them and do not have internal state. Options 2, 3, and 4 are not accurate descriptions of this difference.

You're building a real-estate application where users can view properties on a map. Which third-party service would be best for this map integration?

  • Google Maps
  • Instagram Maps
  • LinkedIn Maps
  • Twitter Maps
Google Maps is a widely-used and robust mapping service that provides a rich set of APIs for integrating maps into applications. It offers features like geocoding, real-time updates, and street view, making it an excellent choice for mapping needs in a real-estate application. While other social media platforms may have location features, they are not suitable for this specific task.

To integrate interactive maps into a React application, many developers use the ________ library.

  • React Map
  • Mapbox React
  • React-Leaflet
  • React-Map
Many developers use the "React-Leaflet" library to integrate interactive maps into a React application. React-Leaflet is a popular library for working with Leaflet, a widely-used mapping library for JavaScript. It provides React components to create interactive maps with ease. The other options are not as commonly used for this purpose in the React ecosystem.

You are building an e-commerce site, and you want to ensure that if a single product's details fail to load, it doesn't crash the entire product listing page. How can you achieve this using React features?

  • Use a "try-catch" block within the product details component to handle errors and display a user-friendly message in case of failure.
  • Implement a global error handler at the top level of your application that intercepts errors and displays a generic error message.
  • Utilize React Suspense to suspend rendering of the product details until the data is successfully loaded, preventing any potential errors.
  • Wrap the product details component with an error boundary that gracefully handles any errors occurring within it.
To ensure that a single product's details failing to load doesn't crash the entire page, you can use React Suspense to suspend rendering until the data is successfully loaded. This prevents any potential errors from propagating up and crashing the page. The other options are less suitable for this specific scenario. A "try-catch" block (Option 1) may not prevent rendering issues, a global error handler (Option 2) is too broad, and an error boundary (Option 4) only catches errors within its component tree.

You're building an application where a specific UI element needs to break out from its parent's stacking context, due to the parent's z-index constraints. What React feature would you leverage to achieve this?

  • React Context
  • React Fragments
  • React Hooks
  • React Portals
To break out of a parent's stacking context and render a UI element outside its parent, you can use React Portals. Portals allow you to render content at a different location in the DOM hierarchy, which is useful for scenarios like modals or tooltips that need to overlay other elements without being affected by parent z-index constraints.

To update a service worker, you often need to change its ________.

  • Configuration
  • Hosting environment
  • JavaScript code
  • Service worker version
To update a service worker, you typically need to change its JavaScript code. Service workers are scripts that run in the background and handle tasks like caching and push notifications. Updating the code allows you to implement new features or bug fixes in the service worker.