ReactJS Basic Questions

Here are the 20+ ReactJS Basic Questions for the beginners to understand the ReactJS.

Q1: Is Node.JS required for ReactJS?

No, you can develop ReactJS based website without NodeJS. First of all, just add the following path in your HTML file and open this HTML in your browser.

Here babel is work as transpiler on client-side but it may slow down the website.
It’s great if ReactJS and Node JS work together. ReactJS is written in JXS and then convert it into JavaScript so that browser can understand the code. ReactJS is front-end (client-side rendering)JavaScript library to build the user interface or component. Node.js provides the runtime environment and finally executes the JavaScript code.

Q2: Is Node.JS recommend for ReactJS?

Yes, It’s recommended because by using  Node.JS you can easily install the packages and manage your application. If you want server-side rendering Node.JS is the best option.

Q3: Is JSX required for ReactJS?

No, It doesn’t need but it would be boring without JSX and also you can lose its benefits and features. It makes ReactJS a lot more stylish. Babel library converts the JSX into JavaScript so you don’t worry about that but remember on production it can be slow down the webpage so it’s not recommended. JSX code should be written in <script type=”text/babel”></script>.

Q4: What is the main difference between ReactJS and AngularJS?

Basically, ReactJS is Javascript library for “View” means contains the set of functions that programmer can call. AngularJS is a pure javascript MVC framework. AngularJS has two-way binding but ReactJS has only one-way binding.

Q5: What is the main difference between ReactJS and React native?

ReactJS is Javascript library and can be rendered on the both client-side and server-side. React native is framework used for build both Android and iOS mobile application at a time.

Q6: What does the mean of virtual DOM in ReactJS?

Basically, to fast the DOM (Document Object Model) manipulation, ReactJS uses virtual DOM. Virtual DOM is synced with the actual DOM.
1 -> Build in-memory virtual DOM (copy of actual DOM) 2 -> Find the differences 3 -> updates the actual DOM (browser’s DOM).

Q7: Can perform the run-time debugging in ReactJS?

No, Only compile-time debugging can be performed.

Q8: Why use Redux in ReactJS?

Redux uses to store the “state” between the components. Redux manages the app states by the help of Reducers and Dispatcher. Redux base on the unidirectional flow and has a single store.

Q9: What is the main difference between the Functions and Class in React?

In ReactJS component can be based on Function or Class. A function-based component is stateless and therefore works as usual Javascript functions. A class-based component has own state and create the object or instance from Class.

Q10: What is the most important method in React.Component class?

render() method must be included in ReactJS class because render(){} method returns the JSX.

Q11: What is the best combination with ReactJS?

It depends on you. Use Node.JS as a server, ExpressJS as back-end web application framework and Webpack as a bundler. MERN

Q12: Why are using Webpack in ReactJS applications?

Webpack uses to bundling the ReactJS modules, javascript libraries, CSS files, and even images. For server-side rendering, we provide the entry point javascript

and output (build folder) in webpack.config.js. We run the Webpack command to build the single js file and then upload that created js file on the server

and given the file path on our HTML page.

Q13: Does google crawl the ReactJS application?

Google can crawl the ReactJS website but remember that your most important content (keywords) should be load initially as possible. Should use ES6 Promise.

Q14: Is ReactJS component render only on the client side?

It depends on your coding. ReactJS content can be rendered on both ends (server/client).

Q15: Is ReactJS support single page application (SPA)?

ReactJS is best for single page application. You just know how to route the react component and how to use the Redux.

Q16: How to create the component in ReactJS?

Create a class and then extend it with ‘Component’.

Q17: What is the difference between props and state in ReactJS?

Props are just like properties and use to pass the data from parent to child only so, that’s why it is uni-directional data flow. Props value can’t be changed but a parent can change the props value.
State works within the component. If any changes occur in ‘state’ then component render again. States can be changed but a parent can’t change the child states.

Q18: What does the mean of uni-directional data flow in ReactJS?

It means data flow from the parent component to the child component. For the reason that it maximizes the performance of the application.

Q19: How do write the UI test case in ReactJS?

We can use Jest javascript testing framework. There are many frameworks to testing.

Q20: What does the mean of ReactNode?

Anything which render in React called as ReactNode. For example ReactElement, numbers, strings and Array of React Elements.

Q21: How can handle the mouse wheel event?

onWheel event is used.

Q22: What should if I want to render nothing?

You may use null or false or true or undefined.

Q23: Why are use PropTypes in ReactJS?

Basically, PropTypes are used for data validation.

Q24: What is the role of Flux in ReactJS?

Flux is the complement of ReactJS. Flux is an architecture to make the ReactJS application like MVC but with uni-directional data flow support.

——– ReactJS Basic Questions & Answers ———

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