Hello, everybody! It is not a secret that employers often ask different tricky questions on the interview. Even if you are a good specialist, you can be confused. So, if you are going to have an interview in React JS development company, you are in the right place. Today I will give you top ReactJS development interview questions and answers for 2020.
Question 1: Why should we use ReactJS?
As you can see, this question allows you to express your opinion about React JS. You can just name the best features of React and that will be enough. For example, they include:
Virtual DOM instead of real DOM;
Speed and scalability;
JSX ensures code that is easy to read and write;
and so on.
Question 2: What is a JSX?
In the previous React JS question, we already mentioned clear JSX code as one of the advantages. But to understand what we are talking about, you need to understand what JSX is all about.
Question 3: Explain the distinction between Real DOM and Virtual DOM.
To understand some special texts DOMs are used. DOM is a Document Object Model. For instance, the DOM is used to represent HTML texts when it comes to web development.
In React it is used as a Virtual DOM. This is something in the nature of a simplified copy of React HTML texts. Furthermore, it is also a new presentation of a real DOM.
Question 4: Can web browsers Read JSX?
No, they cannot.
Question 5: What are the life cycle stages of components?
While this can be seen as one of the most subjective React interview questions, there is still a consensus around the lifecycle of React JS components.
This lifecycle consists of three stages: initialization, updating states, and destruction.
Question 6: What is the distinction between React JS and React Native?
It is very important for you to know not only about ReactJS but also other available libraries and frameworks. For instance, React Native is also beginning to gain popularity, so it's also worth paying attention to.
Question 7: What is the key attribute for when rendering lists?
Keys help React determine which items have been modified, added, or deleted. They must be specified so that React can map the elements of the array over time.
The best way to choose a key is to use a string that will clearly distinguish the list item from its neighbours. Most often you will use the ID from your data as keys. When you do not have specified IDs for the list, you can use the element index as a key as a last resort.
Question 8: What is Redux?
Question 9: What is the Flux?
Flux makes it possible for you to build various layers of information (data) within your apps. Flux is very important as it was created by Facebook along with React.
Question 10: What is setState used for?
When the setState command is called, the object is interfolded into the current state. As soon as this happens, the UI will be updated to the new state.
This question is a good sample of a more technical question on React.
Question 11: What is a State?
As strange as it may be, this question is considered to be one of the most difficult.
Remember how we talked about the lifecycle of a component? States are objects that include certain data within them. You have to remember here is that data can transform throughout the lifecycle of a component, depending on the events that affect it.
We have mentioned most of the React questions you might come across during an interview. In this post, you can find answers to ReactJS interview questions which are both the most basic and more advanced. So, now you are ready to interview)
If you learn all this information, you will be one step closer to your goal. Wish you all the best! Goodbye!