React Interview Questions and Answer 2023 Edition For College Final Year Students., Cheat Sheet of Javascript programming

Download React Interview Questions and Answer 2023 Edition For College Final Year Students. and more Cheat Sheet Javascript programming in PDF only on Docsity! 1 | P a g e Top 50 React Interview Questions and Answers 2 | P a g e Following are frequently asked React interview questions for fresher’s as well as experienced React developers. 1) What is Reactjs? React is a JavaScript library that makes building user interfaces easy. It was developed by Facebook. 2) Does React use HTML? No, It uses JSX, which is similar to HTML. 3) When was React first released? React was first released on March 2013. 4) Give me two most significant drawbacks of React  Integrating React with the MVC framework like Rails requires complex configuration.  React require the users to have knowledge about the integration of user interface into MVC framework. 5) State the difference between Real DOM and Virtual DOM Real DOM Virtual DOM It is updated slowly. It updates faster. It allows a direct update from HTML. It cannot be used to update HTML directly. It wastes too much memory. Memory consumption is less 6) What is Flux Concept In React? Facebook widely uses flux architecture concept for developing client-side web applications. It is not a framework or a library. It is simply a new kind of architecture that complements React and the concept of Unidirectional Data Flow. 5 | P a g e 20) Explain synthetic event in React js Synthetic event is a kind of object which acts as a cross-browser wrapper around the browser’s native event. It also helps us to combine the behaviors of various browser into signal API. 21) What is React State? It is an object which decides how a specific component renders and how it behaves. The state stores the information which can be changed over the lifetime of a React component. 22) How can you update state in react js? A state can be updated on the component directly or indirectly. 23) Explain the use of the arrow function in React The arrow function helps you to predict the behavior of bugs when passed as a callback. Therefore, it prevents bug caused by this all together. 24) State the main difference between Pros and State The main difference the two is that the State is mutable and Pros are immutable. 25) Explain pure components in React js Pure components are the fastest components which can replace any component with only a render(). It helps you to enhance the simplicity of the code and performance of the application. 26) What kind of information controls a segment in React? There are mainly two sorts of information that control a segment: State and Props State: State information that will change, we need to utilize State. Props: Props are set by the parent and which are settled all through the lifetime of a part. 27) What is 'create-react-app'? 'create-react-app' is a command-line tool which allows you to create one basic react application. 6 | P a g e 28) Explain the use of 'key' in react list Keys allow you to provide each list element with a stable identity. The keys should be unique. 29) What are children prop? Children props are used to pass component to other components as properties. 30) Explain error boundaries? Error boundaries help you to catch Javascript error anywhere in the child components. They are most used to log the error and show a fallback UI. 31) What is the use of empty tags ? Empty tags are used in React for declaring fragments. 32) Explain strict mode StrictMode allows you to run checks and warnings for react components. It runs only on development build. It helps you to highlight the issues without rendering any visible UI. 33) What are reacted portals? Portal allows you to render children into a DOM node. CreatePortalmethod is used for it. 34) What is Context? React context helps you to pass data using the tree of react components. It helps you to share data globally between various react components. 35) What is the use of Webpack? Webpack in basically is a module builder. It is mainly runs during the development process. 36) What is Babel in React js? Babel, is a JavaScript compiler that converts latest JavaScript like ES6, ES7 into plain old ES5 JavaScript that most browsers understand. 7 | P a g e 37) How can a browser read JSX file? If you want the browser to read JSX, then that JSX file should be replaced using a JSX transformer like Babel and then send back to the browser. 38) What are the major issues of using MVC architecture in React? Here are the major challenges you will face while handling MVC architecture:  DOM handling is quite expensive  Most of the time applications were slow and inefficient  Because of circular functions, a complex model has been created around models and ideas 39) What can be done when there is more than one line of expression? At that time a multi-line JSX expression is the only option left for you. 40) What is the reduction? The reduction is an application method of handling State. 41) Explain the term synthetic events It is actually a cross-browser wrapper around the browser’s native event. These events have interface stopPropagation() and preventDefault(). 42) When should you use the top-class elements for the function element? If your element does a stage or lifetime cycle, we should use top-class elements. 43) How can you share an element in the parsing? Using the State, we can share the data. 44) Explain the term reconciliation When a component's state or props change then rest will compare the rendered element with previously rendered DOM and will update the actual DOM if it is needed. This process is known as reconciliation.