10+ Volvo Interview Questions and Answers

Lazy loading is a technique used to defer loading non-essential resources until they are needed.

• Lazy loading helps improve performance by only loading resources when they are required.

• In React, lazy loading can be implemented using React.lazy() and Suspense components.

• Example: const MyComponent = React.lazy(() => import('./MyComponent'));

• Example: Loading...}>

React routing is a way to handle navigation in a React application by defining routes and rendering components based on the URL.

• React routing allows for declarative routing, where routes are defined using JSX elements.

• It enables dynamic routing based on the URL, allowing for different components to be rendered based on the route.

• React Router is a popular library for handling routing in React applications.

• Unlike conventional routing methods, React routing is more efficient as ...read more

Difference between React.memo vs use memo vs useCallback

• React.memo is a higher-order component that memoizes a functional component

• useMemo is a hook that memoizes a value

• useCallback is a hook that memoizes a function

• React.memo and useMemo are used for performance optimization

• useCallback is used to prevent unnecessary re-renders

Redux is a predictable state container for JavaScript apps.

• Redux is a state management library for JavaScript applications.

• It helps in managing the state of the application in a predictable way.

• Redux stores the entire state of the application in a single immutable object.

• Actions are dispatched to update the state, and reducers specify how the state changes in response to actions.

• Redux is commonly used with React to manage the state of complex applications.

• Example: In a shoppi...read more

Virtual DOM is a lightweight copy of the actual DOM in memory, used by React to improve performance by minimizing actual DOM manipulations.

• Virtual DOM is a concept where a lightweight copy of the actual DOM is kept in memory.

• React uses Virtual DOM to improve performance by minimizing actual DOM manipulations.

• When state changes in a React component, a new Virtual DOM representation is created and compared with the previous one to determine the minimal changes needed to update ...read more

useMemo is used for memoizing expensive calculations, while React.memo is used for memoizing functional components.

• useMemo is a hook used to memoize expensive calculations and only recompute the value when the dependencies change.

• React.memo is a higher order component used to memoize functional components and prevent unnecessary re-renders.

• useMemo is typically used for optimizing performance by caching values, while React.memo is used for optimizing re-renders by shallowly co...read more

React hooks are functions that allow functional components to use state and lifecycle methods.

• Introduced in React 16.8

• useState() hook for managing state

• useEffect() hook for lifecycle methods

• useContext() hook for accessing context

• useReducer() hook for managing complex state

• Custom hooks for reusable logic

Reconciliation is the process of updating the virtual DOM with changes made to the actual DOM.

• Reconciliation is a process that React uses to update the UI efficiently.

• It compares the previous and current states of the virtual DOM and updates only the necessary changes to the actual DOM.

• Reconciliation is a key feature of React that makes it fast and efficient.

• For example, when a user types in a search box, React updates only the search results and not the entire page.

SSR in React is implemented using server-side rendering to pre-render React components on the server before sending them to the client.

• Use libraries like Next.js or Gatsby to implement SSR in React.

• Configure server to render React components on the server side.

• Optimize server-side rendering for performance by caching rendered components.

map returns a new array with modified elements, forEach does not return anything and just iterates over the array.

• map returns a new array with the results of calling a provided function on every element in the array.

• forEach executes a provided function once for each array element without returning anything.

• Example: const numbers = [1, 2, 3]; const doubled = numbers.map(num => num * 2); // doubled will be [2, 4, 6]; numbers.forEach(num => console.log(num)); // will print 1, 2,...read more

Currying is a technique in functional programming where a function with multiple arguments is transformed into a sequence of functions, each taking a single argument.

• Currying helps in creating reusable functions and improving code readability.

• It allows partial application of functions, where some arguments are fixed and others are left to be provided later.

• Example: const add = (a) => (b) => a + b; add(2)(3) will return 5.

A Higher Order Component (HOC) is a function that takes a component and returns a new component with additional functionality.

• HOCs are used to share code between components, add additional features, or modify behavior.

• They are commonly used for tasks like authentication, logging, and data fetching.

• Example: const withAuth = (WrappedComponent) => { return class extends React.Component { render() { return ; } };

A closure function is a function that has access to its own scope, as well as the outer scope in which it was defined.

• A closure function can access variables from its outer scope even after the outer function has finished executing.

• Closures are commonly used to create private variables in JavaScript.

• Example: function outerFunction() { let outerVar = 'I am outer'; return function innerFunction() { console.log(outerVar); }; }

• Example: const closureExample = outerFunction(); clos...read more

A custom hook is a reusable function that allows you to extract component logic into a separate function.

• Custom hooks start with 'use' keyword.

• Custom hooks can call other hooks if needed.

• Custom hooks can be shared and reused across multiple components.