For fetching data before rendering a component in a route, you might use the React Router's ________ method.
- fetchComponent
- fetchRoute
- preload
- useEffect
To fetch data before rendering a component in a route with React Router, you can use the preload method. This method allows you to load data asynchronously and ensure it's available before rendering the component associated with the route. Using preload helps improve user experience by reducing unnecessary delays.
How does React handle events differently from plain JavaScript, especially considering browser compatibility issues?
- React directly binds events to DOM elements.
- React relies on browser-specific event APIs.
- React uses a virtual DOM for event handling.
- React uses event delegation for all events.
React handles events differently by using a virtual DOM. It creates event listeners at the root level and uses a synthetic event system to manage event handling. This approach abstracts browser-specific issues and ensures consistent behavior across browsers. It does not directly bind events to DOM elements as in plain JavaScript. This difference is crucial for managing cross-browser compatibility.
When a change is made to an immutable data structure, it creates a new version without altering the original. This principle is known as ________.
- Alterability
- Changeability
- Immutability
- Mutation
When a change is made to an immutable data structure, it creates a new version without altering the original data. This principle is known as "Immutability." Immutable data structures are essential in functional programming to ensure predictable and safe data manipulation.
When fetching data from an API, the ________ pattern in React helps handle loading, error, and success states efficiently.
- Container-Component Pattern
- Higher-Order Component Pattern
- Render Props Pattern
- State Pattern
When fetching data from an API, the Render Props pattern in React helps handle loading, error, and success states efficiently. This pattern involves rendering a component with a function as a child, allowing it to pass data and behavior to the children components. This is commonly used to manage the state and UI for API requests. The other options (Container-Component, Higher-Order Component, and State patterns) are related to React but do not specifically address API data fetching and state handling.
For type-safe operations in React components, props, and state, developers can utilize ________ to add static typing.
- ES6
- Flow
- JavaScript
- TypeScript
Developers can use "TypeScript" to add static typing to React components, props, and state. TypeScript is a statically typed superset of JavaScript, which helps catch type-related errors at compile time, making React code more robust and maintainable.
What is the main advantage of using computed properties in MobX?
- Computed properties simplify the setup process of MobX stores.
- Computed properties allow for asynchronous state updates.
- Computed properties provide a performance optimization by caching results.
- Computed properties are used for data persistence.
The main advantage of using computed properties in MobX is that they provide a performance optimization by caching results. Computed properties automatically recompute only when their dependencies change, improving the efficiency of your application. The other options do not accurately describe the primary advantage of computed properties in MobX.
When considering Server-Side Rendering (SSR) in React, which framework is widely recognized for this purpose?
- Angular Universal
- Gatsby.js
- Next.js
- Vue Server Renderer
Next.js is widely recognized for Server-Side Rendering (SSR) in React applications. It provides an out-of-the-box solution for SSR, making it easier to implement server-side rendering in React applications. While other frameworks like Angular Universal and Gatsby.js also support SSR, Next.js is particularly popular in the React ecosystem for this purpose.
Which React feature works in tandem with React.lazy to display fallback UI while a component is being lazily loaded?
- React.Suspense
- React.Fallback
- React.LazyUI
- React.Loading
React.Suspense is the React feature that works with React.lazy to display a fallback UI while a component is being lazily loaded. This helps improve the user experience by showing a loading indicator or a fallback UI while the required component is fetched and rendered lazily. Other options like React.Fallback, React.LazyUI, and React.Loading are not standard React features.
Which React feature can be combined with the Context API to optimize performance in components that consume context values?
- React Fragments
- React Hooks
- React Portals
- React Suspense
To optimize performance in components that consume context values, you can combine the Context API with React Hooks. Specifically, you can use the useContext hook to access context values. This hook allows you to consume context values without the need for a higher-order component, improving code readability and maintainability. React Portals, React Fragments, and React Suspense are not typically used for optimizing context consumption performance.
Which library is popularly used in the React ecosystem to provide immutable data structures?
- Immutable.js
- Mutable.js
- React Immutable Structures
- Unchangeable.js
Immutable.js is a popular library in the React ecosystem used to provide immutable data structures. It offers a set of data structures that can be used in place of JavaScript's native data structures, making it easier to work with immutable data in React applications. The library is well-suited for managing state in React components and is widely adopted in the React community.
Consider a scenario where you have a deep nested component structure, and you need to break out of the current styling context (like an overflow hidden container). Which React feature would you use?
- Context API
- Portals
- Redux
- useMemo hook
To break out of the current styling context, you can use React Portals. Portals allow you to render a component at a different place in the React tree, often outside of the DOM hierarchy of the parent component, which is useful for situations like modals or tooltips. Context API and Redux are state management solutions, not specifically designed for this purpose. The useMemo hook is used for memoization, optimizing the rendering performance of components.
Which of the following best describes the purpose of the render method in class components?
- It defines component lifecycle methods
- It is used to fetch data
- It is used to set the state
- It returns the UI to be rendered from the component
In React class components, the render method is responsible for returning the JSX (or UI elements) that represent the component's UI. It does not fetch data, set state, or define lifecycle methods directly.