Rectras – React JS Interview Questions

Here is the list React JS Interview Questions which are recently asked in Rectras company. These questions are included for both Freshers and Experienced professionals. Our React JS Training has Answered all the below Questions.

1.How to create components in React?

When creating a React component, the component's name must start with an upper case letter. The component has to include the extends React.Component statement, this statement creates an inheritance to React.Component, and gives your component access to React.Component's functions. The component also requires a render() method, this method returns HTML.

2. What is React?

React is an open-source JavaScript library that is used to develop complex and interactive web and mobile UI. It is used for building web browser apps, creating dynamic libraries and building UI's that are perfectly equipped to render large datasets.

3. Characterize ReactJs and Its highlights.

Virtual DOM and JSX.
One-way data binding.
React native and declarative UI.
Component-based architecture.
Speed and efficiency, flexibility.

4. For what reason would it be advisable for us to utilize React, tell its points of interest as well?

The React basically allows developers to utilize individual parts of their application on both client-side and the server-side, which ultimately boosts the speed of the development process.

5. Enroll React constraints on the off chance that you know any?

React is a hug libraries and not structure.
Use React to comprehend this library as it is substantial in size.
Very hard to comprehend this library.
Inline templating and JSX.

6. Clarify Virtual DOM of React and how can it function?

The Virtual DOM is a node tree that lists elements and their attributes and content as objects and properties. React's render() method creates a node tree from React components and updates this tree in response to mutations in the data model, caused by actions.

7. Separate among React and Angular.

Angular is a full-fledged framework, while React is a library. React. js uses virtual DOM and one-way data binding while Angular operates on real DOM & two-way data binding. There's also a difference in bundle size (React's smaller) and speed (React works a bit faster).

8. What is the importance of the announcement ‘In React, everything is part’?

Components are the building blocks of a React application's UI. These components split up the entire UI into small independent and reusable pieces. Then it renders each of these components independent of each other without affecting the rest of the UI.

9. Think about props and state.

Props are immutable which lets React do fast reference checks. It is used to pass data down from your view-controller. It is used this to pass data to child components. State should be managed in your view-controller. It is mutable and has worse performance. It should not be accessed from child components.

10. What is the best approach to install at least two parts?

React and React DOM can be split into two different libraries. HOCs are the best way to share behaviour between React Components.

11. By what method can the segment state be refreshed?

state = initialState; requires you never to mutate your state, otherwise you'll pollute initialState and make a reset impossible. If you can't avoid mutations, then you'll need to create a copy of initialState in the constructor. (Or make initialState a function, as per getInitialState().

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12. Think about stateful and stateless segments.

Stateful and stateless components have many different names. The literal difference is that one has state, and the other doesn't. That means the stateful components are keeping track of changing data, while stateless components print out what is given to them via props, or they always render the same thing.

13. What are the periods of the lifecycle of React’s segment?

Each component in React has a lifecycle which you can monitor and manipulate during its three main phases. The three phases are: Initialization, Mounting, Updating, and Unmounting.

14. What are the techniques for React segment lifecycle?

React lifecycle methods are as the series of events that happen from the birth of a React component to its death. Every component in React goes through a lifecycle of events. I like to think of them as going through a cycle of birth, growth, and death.

15. What is the state in react js?

The state is an instance of React Component Class can be defined as an object of a set of observable properties that control the behavior of the component. In other words, the State of a component is an object that holds some information that may change over the lifetime of the component.

16. What are props in react js?

The term render prop refers to a technique for sharing code between React components using a prop whose value is a function. A component with a render prop takes a function that returns a React element and calls it instead of implementing its own render logic.

17. What is different b/w super() and super(props)?

Component's constructor() function gets called, we call super(props).super(props) is a reference to the parents constructor() function, that's all it is. We have to add super (props) every single time we define a constructor() function inside a class-based component.

18. What is the super keyword in react?

Super() is used to call the constructor of its parent class. This is required when we need to access some variables of its parent class. Props: It is a special keyword that is used in react stands for properties. Used for passing data from one component to another.

19. Real Disadvantages of utilizing React.

Disadvantage of React JS

The high pace of development.
Poor Documentation.
View Part.
JSX as a barrier.

20. What are the periods of the lifecycle of React’s part?

Each component in React has a lifecycle which you can monitor and manipulate during its three main phases. The three phases are: Initalization, Mounting, Updating, and Unmounting.

21. What are the strategies for React part lifecycle?

React lifecycle methods as the series of events that happen from the birth of a React component to its death. Every component in React goes through a lifecycle of events. I like to think of them as going through a cycle of birth, growth, and death.

22. What is yield catchphrase in JavaScript?

Yield keyword is used to resume or pause a generator function asynchronously. A generator function is just like a normal function but the difference is that whenever the function is returning any value, it does it with the help of 'yield' keyword instead of return it.

23. What are the means to Setup React Environment?

Scaling many files and components.
Using third-party libraries from npm.
Early detection of common mistakes.
Live-editing CSS and JS in development.
Optimizing the output for production.

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Rectras React JS Interview Questions