How do you create HOC using render props?

  • By passing a function as a prop to the higher-order component
  • By returning a new component from the higher-order component
  • By using the withRenderProp() method
  • By using the createRenderProp() method
Higher-Order Components (HOCs) are a powerful pattern in React that allow developers to reuse code between components. HOCs can also be implemented using render props, which involves returning a new component from the higher-order component that renders the children using a function prop. This pattern is known as "render prop HOCs" and is a flexible and powerful way to share code between components.

How to create React class components without ES6?

  • By using create-react-class method
  • By using functional components
  • By using the React.Component class directly
The create-react-class method is a way to create React class components without using ES6 syntax. This method allows components to be created using a simple object-based syntax, rather than defining a class and extending the React.Component class. The create-react-class method is useful for creating components that do not require complex logic or state management.

What is the purpose of registerServiceWorker in React?

  • To register a new service worker with the browser
  • To enable client-side caching of static assets
  • To enable offline access to the application
  • All of the above
registerServiceWorker is a utility function provided by the Create React App tool that registers a new service worker with the browser. This service worker enables client-side caching of static assets and enables offline access to the application.

What are the lifecycle methods going to be deprecated in React v16?

  • componentWillMount and componentWillReceiveProps
  • componentWillMount and componentWillUpdate
  • componentWillReceiveProps and componentWillUpdate
  • componentWillUpdate and componentDidUpdate
The "componentWillReceiveProps" and "componentWillUpdate" lifecycle methods are going to be deprecated in React v16. These methods will be replaced with new lifecycle methods that are more efficient and easier to reason about. The new methods are "getDerivedStateFromProps" and "getSnapshotBeforeUpdate".

How to get history on React Router v4?

  • Use the "history" object provided by the "history" module
  • Use the "history" object provided by the "react-router-dom" module
  • Use the "this.history" object provided by the router
  • Use the "this.props.history" object passed to the component
In React Router v4, you can get the history object by using the "this.props.history" object passed to the component. This object contains the current history of the router, including the current location, previous locations, and navigation history. You can use this object to programmatically navigate, access the current URL, or manage the browser history.

How to dispatch an action on load?

  • Use a lifecycle method in a component
  • Use a middleware
  • Dispatch the action in the reducer
To dispatch an action on load, you can use a lifecycle method in a React component, such as componentDidMount(). This method is called once the component has mounted, allowing you to dispatch an action to the Redux store.

What is the difference between Flow and PropTypes?

  • Flow is a type checking tool for JavaScript, while PropTypes is a runtime type checking library
  • Flow and PropTypes are the same thing
  • PropTypes is a type checking tool for JavaScript, while Flow is a runtime type checking library
  • PropTypes is a runtime validation library for React components
The main difference between Flow and PropTypes is that Flow is a type checking tool for JavaScript that checks types at compile-time, while PropTypes is a runtime type checking library for React components that checks types at runtime. Flow is particularly useful in large codebases where it can be difficult to keep track of all the variables and function calls, while PropTypes is useful for catching errors in React components at runtime.

What is suspense component?

  • A component for handling errors in React
  • A component for delaying rendering in React
  • A component for handling lazy loading in React
  • A component for handling forms in React
The suspense component is a component for delaying rendering in React. The suspense component allows components to wait for asynchronous data to load before rendering, improving the user experience and reducing loading times. The suspense component is typically used with code splitting and lazy loading to enable on-demand loading of code.

You are implementing error handling in an Express application, and you notice that asynchronous errors are not being caught by your error-handling middleware. How should you modify your error-handling approach to ensure that asynchronous errors are caught?

  • Wrap asynchronous code with try-catch blocks
  • Use the next function with async/await middleware
  • Disable asynchronous error handling
  • Increase the Node.js event loop size
In Express.js, asynchronous errors are not automatically caught by synchronous error-handling middleware. To catch asynchronous errors, you should use the next function with async/await middleware to ensure that errors occurring in asynchronous code are properly handled by your error-handling middleware. Wrapping asynchronous code with try-catch blocks won't work for middleware functions.

JavaScript’s ______ operator can be used to create a new object with the specified prototype object and properties.

  • New
  • Prototype
  • Object.create()
  • Construct
JavaScript's "Object.create()" operator can be used to create a new object with the specified prototype object and properties. This method is commonly used for creating objects with specific prototypes in JavaScript, allowing for more control over inheritance and object composition.