Which of the following describes the main purpose of Render Props in React?
- Defining component propTypes.
- Managing component state.
- Reusing component logic.
- Styling components.
The main purpose of Render Props in React is reusing component logic. This technique allows you to pass a function as a prop to a child component, enabling that child to render something based on the parent's state or logic. It's particularly useful for sharing behavior or functionality between components without tying them to each other. While managing state can be a part of using Render Props, it's not the primary purpose.
In class components, the method used to fetch new props and state and decide whether a re-render should occur is ________.
- componentDidUpdate
- componentFetchUpdate
- componentWillUpdate
- shouldComponentUpdate
In class components, the method used to fetch new props and state and decide whether a re-render should occur is shouldComponentUpdate. This method allows you to control the re-rendering process by returning true or false based on conditions you specify. It's a key method for optimizing the performance of class components by preventing unnecessary re-renders.
You're building a blog with Next.js. You want each blog post to have a unique URL based on its title, but you don't want to create a new page component for each post. How would you achieve this?
- Use dynamic routing with Next.js by creating a [slug].js page that fetches the blog content based on the slug.
- Use static site generation (SSG) for all blog posts to create individual HTML files for each post during build time.
- Create a single page component and use query parameters in the URL to determine which blog post to display.
- Use server-side rendering (SSR) to fetch the blog content and render it dynamically based on the requested URL.
To achieve unique URLs for each blog post without creating a new page component for each post, you can use dynamic routing with Next.js by creating a [slug].js page that fetches the blog content based on the slug. This allows you to use a single page component to display different blog posts dynamically based on the URL. Static site generation (SSG) would create separate HTML files for each post, which is not necessary in this case. The other options are not the most efficient ways to achieve this.
In a large-scale React-Redux application, you notice that unnecessary re-renders are affecting performance. Which strategy would be most effective in preventing these unnecessary re-renders?
- Use React's PureComponent for components and connect them with Redux.
- Implement a memoization technique like reselect to compute derived data efficiently.
- Avoid using Redux for state management in large-scale applications and rely on local component state.
- Use Redux's shouldComponentUpdate method to selectively update components.
Implementing a memoization technique like reselect is the most effective strategy for preventing unnecessary re-renders in a large-scale React-Redux application. Reselect allows you to compute derived data efficiently, ensuring that components only re-render when their relevant data changes. While the other options may have their merits, they do not directly address the issue of unnecessary re-renders as effectively as memoization does.
Your application has a route that is accessed infrequently by users, such as an admin dashboard. How can you optimize the loading of this particular route's component?
- Bundle the admin dashboard component with the main application bundle.
- Code-split the admin dashboard component and load it asynchronously when users access the route.
- Pre-render the admin dashboard component on the server side.
- Use client-side rendering to ensure the admin dashboard component loads quickly.
To optimize the loading of an infrequently accessed route like an admin dashboard, you should code-split the admin dashboard component and load it asynchronously when users access the route. This approach avoids loading unnecessary code upfront, improving performance. Client-side rendering, bundling with the main bundle, and server-side pre-rendering are not optimal for this scenario.
When using React Transition Group, which component is useful for animating the presence of a component over time, especially when it's being added or removed?
- CSSTransition
- AnimatePresence
- TransitionPresence
- AnimateComponent
When using React Transition Group, the AnimatePresence component is especially useful for animating the presence of a component over time, especially when it's being added or removed from the DOM. It helps manage animations for components entering or exiting, providing a smooth and controlled transition experience. The other options are not standard components in React Transition Group.
You're building a tooltip component that should be flexible enough to display different content based on where it's used. Which pattern would best allow for this flexibility?
- Decorator Pattern
- Factory Method Pattern
- Observer Pattern
- Singleton Pattern
The Factory Method Pattern is the best choice for creating a tooltip component that can display different content based on its usage context. It allows you to define an interface for creating objects but lets subclasses alter the type of objects that will be created. In this case, different tooltip content can be created by subclasses while still adhering to a common interface. The other patterns listed are not typically used for this specific purpose.
The Context API provides a way to pass data through the component tree without having to pass props down manually at every level using the ________ and ________ mechanism.
- Provider and Consumer
- State and Props
- Render Props and HOC
- Redux and MobX
The Context API in React provides the Provider and Consumer components, which allow data to be passed through the component tree without the need to manually pass props down at every level. This mechanism simplifies state management in complex React applications. While the other options are related to React state management, they do not specifically describe the Context API mechanism.
Which hook would be best suited to manage the global state of an application?
- useContext
- useEffect
- useRef
- useState
The hook best suited to manage the global state of an application is useContext. useContext provides a way to share data (state) between components without prop drilling. It is often used in combination with useReducer or useState to manage global application state. While the other hooks have their use cases, useContext is specifically designed for global state management in React applications.
In React, ______ and Suspense are used together to implement lazy loading of components.
- React.lazy()
- useEffect() and Fetch
- useState() and Axios
- useMemo() and Promises
In React, React.lazy() and Suspense are used together to implement lazy loading of components. React.lazy() allows you to dynamically load a component when it's needed, and Suspense is used to handle loading states. The other options are not directly related to lazy loading components.
How do CSS-in-JS libraries like styled-components handle server-side rendering (SSR) for styling?
- They do not support SSR.
- They generate inline styles on the server-side.
- They rely on external CSS files for SSR.
- They dynamically load styles on the client-side after rendering.
CSS-in-JS libraries like styled-components generate inline styles on the server-side, which are then included in the HTML response. This approach ensures that styles are applied during the initial render on the server, enhancing performance and SEO. The other options do not accurately describe how CSS-in-JS libraries handle SSR.
Which popular React framework is primarily used for Server-Side Rendering?
- Angular
- Next.js
- Redux
- Vue.js
Next.js is a popular React framework primarily used for Server-Side Rendering (SSR). It simplifies the process of building SSR-enabled React applications, providing features like automatic code splitting and routing. While Redux is a state management library for React, Angular is a different framework, and Vue.js is another JavaScript framework, they are not primarily used for SSR in the same way Next.js is.