React Native Interview Questions and Answers: Your Hiring Roadmap

21 min read
Jan 15, 2021
React Native Interview Questions and Answers: Your Hiring Roadmap
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You’ve probably already heard a lot about React Native. This is all because it has become very popular and confidently captured the world under its wing. Facebook created this open-source framework in 2015.

We can say that React Native is quite new, but in this relatively short period, which has not yet reached the age of 5, it has become popular with both developers and customers around the world. Today, we can already talk about the maturity of the framework itself and the builders that make cross-platform development of mobile applications possible.

In the market, specialists in software development are becoming so popular that we decided to systematize all our knowledge about the recruitment process of these specialists so that you can get acquainted with React Native developer interview questions you need.

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No wonder they say those good employees are worth their weight in gold, just have a quick look at the React Native developers salary. Obviously, you need to spend a lot of effort and energy to find the best of them. Think about what prospects open up before you, if you know in advance React Native interview questions you can ask and analyze the answers of our experts. The React Native interview with desired developers will be more than successful! Are you ready to surf through questions on your big-time React Native interview? Let’s go!

List of The Interview Questions for React Native Developers

Beginners Level Questions

You start the search for talented newcomers. As you know React Native developers must graduate courses. But if they worked as JavaScript developers and knew the basics, you would have more opportunities to finish the interview successfully and hire talents in the team. There is a chance that developers already have some kind of portfolio.

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A loyal company needs to create conditions for the continuous development of its specialists so that they penetrate deeper into the selected technologies. You should understand that when hiring a beginner-level specialist, you need an experienced mentor who can help and give answers to questions. In such a bundle, a novice specialist will quickly reach a higher level.

While looking for talented people, be attentive to those who are minutely prepared to answer the technical interview questions that each company needs to ask. We know that finding reliable dedicated professionals is never easy, and you need to understand that finding your people is a huge challenge that not every company can overcome.

To make your task a little easier, here you can view the best React Native interview questions for beginners and pay attention to the correct answers that will help you to find a brilliant specialist in the React Native sphere.

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What is React Native Modal?

It is a basic component that opens the content above the closing view. The modal window by default contains its own view, but at the same time it has such properties as visible, animationType, transparent, onRequestClose.

Who needs React Native?

Since React Native broke into the world of web and mobile development, with the support of a reputable Facebook, the market is created just a snowball from new libraries and frameworks. Without false modesty we can say that it is almost for everything: from startups to huge enterprises, for example Discord and Skype. That’s why our React Native developer interview questions are exactly what should not be left out.

It managed to achieve a declarative approach to interface development without sacrificing performance and you pay for one app, receiving two. Impressive, isn’t it? The new trend of paying for less, getting more captures more and more supporters every year. At this time there are lots of apps and the world will never be the same again.

What is the difference between React and React Native?

When React is a JavaScript library, React Native is a framework, using the same principles and similar syntax. It is open-source. We use React for creating Web Applications and UI, while React Native is used for cross-platform mobile applications.

It should also be noted that React works with a domain tree. As for React Native, it does not have a similar analog and the translation process takes place via a bridge to the native iOS and Android modules.

What is Cross-platform application development?

This is a way to create applications that run on multiple operating systems. For example, our React Native team creates one application for both IOS and Android.

What are the main advantages of the framework?

There are lots of advantages in this framework such as:

  • Skills development (when you work with mobile apps, your web skills are running up)
  • You have a great opportunity to create cross-platform mobile applications themselves
  • React Native has components for its native application in JavaScript
  • Easy to integrate with other significant frameworks
  • Speedy and swiftness for mobile applications with responsiveness
  • Ability to use native modules
  • Ability to use lots of native capabilities specific to each platform

How to install React Native?

Try these steps to be succeeded:

  • Start with installing node and watchman
  • Then, install React native CLI with npm
  • Then, Android studio and JDK-java development kit
  • Install Xcode and its Command-line tools
  • Create a React Native project by using the following command:
  • react-native init MyNewProject
  • cd MyNewProject
  • react-native run-ios

How to create a new app?

It doesn’t matter if you have Node 10 or the newest version, it’s easy to start a new app following the next commands:

  • You can utilize npm to install Expo CLI command-line utility:
  • Command: npm install -g expo-cli
  • Run this command to create a New React Native App called “GreatProject”:
  • xpo init GreatProject
  • cd GreatProject
  • npm start # you can also use: expo start

Do we use IDE for React Native?

We use IDE for React Native such as: WebStorm, Visual Studio Code, Atom and so on.

Do you know about core components?

React Native has some core features like View, State, Props, Style, Flexbox, Handing text input, Scrollview, List view, Navigators, and Networking.

What is View?

It is described as a container, which supports layouts such as some touch handling and flexbox.

What is Props?

Properties or props are parameters that we use to configure the component during creation or visualization. Props are immutable and cannot be changed due to the influence of the parent component.

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What is the default props?

Default props allow you to set the default props value for your component. The component will use the default props value if you don’t do that.

What is State?

This is a data type that tracks information. State must be reflected in the constructor. State is changeable and we can change it inside the component.

What are the differences between Props and Stats?

Props are used to configure components when they are created, you can set different parameters for them. The state helps the React to change the output over time in response to events that occur. In contrast to the propes the states recall the details, but it is only the external similarity. State is placed in a single component while properties are read-only for their component.

What is Style?

Style is a core component of this framework. You need it to make your app stylish and interesting for users.

What is Scrollview?

This is a feature that helps you view content using the scroll bar.

What is handling text input?

We refer to it as one of the basic components. It is necessary to get text information (input) from users.

What are navigators?

We use navigators to change one scene to another scene.

What is networking?

It helps you quickly transfer static content from another server or download something from a remote URL. React Native uses Fetch API to provide the function, which is similar to XMLHttpRequest.

What is Flexbox?

Flexbox short for the Flexible Box Module is both a one-dimensional layout and a method whose function is to distribute space between elements within the interface and create practical alignment capabilities. It works with the layout in one dimension at a time and it can occur as a column or row.

What is Render?

Render Props is a technique in which the browser understands Dom nodes like transformed React components.

Why do we use functional components?

A functional component is an ordinary simple JavaScript function that takes props as arguments and returns an element already in the React. The functional component has no state saving and you can’t use setState() in your component. The component does not have its own state and you should not forget about it when working.

Does React Native support HTML?

React Native doesn’t support it.

What is the feature of StyleSheet.create?

StyleSheet.create method fully confirms that the values are immutable and they are created only once.

Mid Level Questions

React Native middle-level specialists see the needs of the customer and can solve different problems of your project. Understanding the client’s goals becomes a top priority for this level of specialists. They have a fairly good command of the English language, which you should check on the React Native interview.

Your dream programmers prepared to use all their knowledge of a foreign language in the interview process for the position of React Native developer. This will reveal them from a new side and show how well they can communicate with the customer directly. Developers must be entrusted with presentations on the work done which gives them more points on React Native interview because they have grown to the next level.

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Here they are already fighting in a higher category and applying for more interesting long-term projects because it is profitable for the company to take cool high-level specialists. They need to prepare for more detailed React Native questions based on previous experience. You are confused and afraid to miss your people because there are so many workers in the market. Which ones do you need?

We are ready to continue to React Native interview questions and answers for experienced, because of the great demand. These questions will be able to give you the right idea if you have difficulties. Our top React Native interview questions are below

What are the component lifecycle methods to React Native?

Lifecycle methods in React Native consist of four phases like assembly (where component is instantiated), update (for statistics and property values), unmount (when the component isn’t needed) and the finish part error finding (while rendering the component).

What is the use of super() inside the constructor of the component?

It is easy to learn from React Native interview questions for experienced that a call is super necessary for the constructor of a child class to work. What are the actions to take?

  1. Call a method
  2. The constructor of the child class will use this reference to work

What do you know about Threads?

As a specialist with experience in interviews, you should talk about three threads. It’s worth starting with the main UI Thread, which can change how the user interface is accessed.

The JavaScript thread, where the JS code is running, handles the business logic, API calls and event handling using touch.

The Shadow background thread is used to calculate the layout.

Animations are being blocked on the JavaScript thread. How to prevent it?

Just add useNativeDriver and tick “true” to the animation options. It will work bypassing the animation to the native thread where it will not be blocked by the JavaScript thread.

How to prevent memory leaks in your app?

Memory leaks aren’t so unusual problems. But if you release timers/listeners added in componentDidMount and handle closure scope, it would be easier to prevent.

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How can you change the size of the element?

Changing the screen size is more than an important feature. And of course, it is available in any mobile application. A different screen size or choose a screen size is an essential aspect of development. In our case we can use the Dimensions component to get the height and width of the device.

Why do we need Bridge?

As you know in React Native, response messages are sent across the bridge. This is a kind of transport interchange for one object to another. Also, the bridge connects threads such as JS and Shadow, creates asynchronous bidirectional links between the thread and the module.

How to optimize a large list of items on FlatList

You can optimize a large list of items using PureComponent. Here the list of the following actions:

  • Use PureComponent on renderItem with bind methods
  • Add keyExtractor property
  • Add pagination
  • Set getItemLayout
  • Set removeClippedSubviews true

How to manage state in your app?

If the app is simple and doesn’t have a lot of dependencies we can use just react hooks.
But if the app will scale I suggest using one of the state management frameworks: MOBX, Redux or Recoil.

Why do we need Redux?

This is a kind of container library that has a predictable state for the JavaScript application and is shared storage. It has the advantage of helping you write consistent applications in different environments and then making it easy to test.

How about Redux action?

It should be remembered that a store is a tool for transferring information from an application to a store based on the operation of actions as a unique source. In turn, the action is a simple JavaScript object that has the type attribute, which indicates the type of action to be performed. Actions are not just a source, but the only way of transfer.

What is Redux reducer?

A change in the application state is a specific function that Redux performs. The action is used by it to determine the change. Redux relies heavily on editor functions that accept previous states and on actions that are necessary to perform the next state.

What is Redux store?

To create a store, you just need to pass the function to reduce the root directory to createStore. What is this store? React Native interview questions and answers for experienced will help you to name that it is an object with multiple methods.

We smoothly move to the harangue, where we store the entire application state tree and see that changing the state inside the tree can be easily done using the initial action on it. As much as we would not like it, but this method is universal and it is the only one.

Practical use of shouldComponenUpdate() methods

This method is very effective for improving performance. practical for performance optimization. Whether we want to render the component a second time or not, the method will return a boolean value. Changing the props is its immediate basis.

Why do we import React in React Native components?

React is useful for JSX in our native components. A class component simply needs a method render () while returning framework elements. Remember that when you render, the class of components must be extended.

Why do we use class and functional components?

An experienced developer is not intimidated by the question of components. They differ in function. The class component will use the ES6 class keyword to create the component and extend the React component class. Functional components are used for lifecycle and state methods. As you can imagine, the functional component is lightweight and productive and does not take up much space.

What is the difference between Scrollview and FlatList?

We paid attention to these elements before. However, let us remember that Scrollview is useful to render small numbers of items instead of FlatList, which is for large items. It will load items immediately after component loading, so all data will mount into RAM.

FlatList is lazier in this contest because it will render items that are visible on the screen. Nevertheless, it creates a great performance which is a real plus.

What is PureComponent?

As you should know, unnecessary rendering occurs when the value of props or State changes, and you should get rid of it using a special PureComponent that handles the settings of the method shouldComponentUpdate ().

What are Hooks? How do they work?

React has just included a new feature called “React Hook”. Hooks are the functions that allow you to use react state & component lifecycle methods in a functional component. It is running without changing it into the class components.

What are the main features for using setState() vs forceUpdate()?

The main difference is in re-rendering. The setState() method is typically used to update the component state with one or more state properties, so forceUpdate() method is just a component to re-render with the force.

High Level Questions

In addition to the ability to create a well-built architecture, a high level React Native developer also needs soft skills while answering React Native interviews. Team building, mentoring and management skills will be especially relevant. Often it is a trained programmer, and not a separate mentor, who becomes a teacher for beginners.

React Native interview questions and answers for experienced developers will be a great test for the nerves and brains of the company and its applicants. You need to understand that high-level specialists have a huge amount of experience, solutions, and skills that they need to show in the process of the tech interview.

Besides, interviews for experienced players are an opportunity not only to solve technical puzzles but also to find all the appropriate and useful answers in a constructive dialogue. Strong professionals require strong questions and unexpected solutions. Such specialists will help you not only stay afloat but also swim against the current, making unthinkable maneuvers on the way to success.

Already wanted to find such wizards? We are always ready to help with our React Native interview questions, you should be well-prepared for hiring. Let’s go to our top experienced questions!

How can you effectively detect memory leaks on the app?

Problems with the memory you can detect with the instruments called Xcode and Android studio, which provide tools to track the memory used by an app. They can be used for testing apps on devices and simulators.

What are the common architectures? What is the difference between them?

This crucial part of the interview questions for React Native developers must be well analyzed. We can say that a job interview for qualified professionals cannot begin without explaining the MVP architecture.

In this architecture, the presenter can only communicate through an interface that is distant from the View, using its business logic. This remoteness helps to model the view in the unit test. It is important that the architecture has two-way dispatching, which allows providing enhanced control over data storage.

The next important architecture is MVC. Here, the controller is responsible for the view that is displayed in response to actions. What is the main difference between the two architectures? In this architecture, each action is interconnected with a call to the controller, and in MVP, actions are directed through the view directly to the presenter.

The action works in conjunction with calling the URL address and is performed under the supervision of the controller. Keep in mind that every action involves a call, and on the other hand, there is a controller that adjusts. Everything will return to the previous mode when the processing is completed by the controller.

What about using the onPress function in React Native View?

Imagine that you have the RN version > 0.55.3. You can add onPress kind of functionality to any View component using onStartShouldSetResponder props.

How about setting the orientation of the app?

There are landscape and portrait modes that almost all mobile devices have. Portrait mode is set by default. Landscape mode is available to us when you rotate the device. If you are uncomfortable with this, you can easily turn off this mode with the code in the AndroidManifest.xml file:
General->DeploymentInfo & select the portrait mode only.
again re-build the project.

Name the function, which is used to pass value between screen in React Native?

Only one this.props.navigation.navigate() method is used to pass value between screen.
Syntax:
this.props.navigation.navigate(‘RouteName’, { /* params go here */ })

Why do we need SafeAreaView?

Its benefit is that it displays nested content and applies padding to reflect the part of the view that is not covered by the tab and navigation bar. it also creates the necessary space and saves the replacement content from the safe area. It is worth noting that the ios_v11 version is suitable for it. Otherwise, this function will not work.

What about the environment variable and its usage?

You can save API keys, environment variables, and even sensitive information in the file .env file. To do this correctly, install the library react-native-dotenv and import the necessary files from the .env file.
We can save environment variables, API keys, or any sensitive information inside the .env file. To use React Native it is necessary to install the library react-native-dotenv. Now we can import environment variables from the .env file.

What is the benefit of Info.plist File?

A dictionary of keys and values can be called in simple words a list of information properties that are stored in a file system with a file extension of a.plist. This is necessary to get information about the operation and settings of the app. So the property list is a structured text file that stores very important configuration information for the associated executable. We code the file using the Unicode UTF-8 encoding and the contents are structured using XML.

How to implement multilanguage support in React Native?

Multilanguage makes the process of translation of the app easier. We can mention Localization like the process of making something local in characters or restricting it to a particular place. We can use third-party npm libraries to use implement localization and Multilanguage.

Stay in touch with *I18n-js * , which is a small library to provide the I18n translations on the JavaScript.

How many ways do you know to handle the app state without Redux?

There are at least two ways to manage the application state. The first easiest one is to use React Context API->The context will help us avoid granularity and provide a way to pass data through the component tree. This will save you from having to manually transfer the prop at each level. It is an impressive effect.

The second method is a bit more complicated. You need to set the global state in your component and top-level functions, which will allow you to update the states. After these actions, the global state and function can be passed as properties to child components using property granularity. You should choose methods based on your experience and the relevant situation.

How to Prepare for an Interview if You are a React Native Developer?

You have decided to become a React Native developer or you are already an experienced specialist. In any case, you need to pass a React Native interview fortunate with confident answers. It is not so difficult to find a company that suits you according to many criteria.

You just have to present yourself at the technical part of the interview for React Native programmer, showing all your strong hard and soft skills, of course, based on our collected top questions that will surely catch up with you at the interview, regardless of your skill level.

React Native is in high demand right now and lots of developers want to study React Native interview questions. If you treat it carelessly, interview questions for React Native developers can be difficult. This is vital, you need not just read questions but also analyze answers. We recommend for the specialist of any level:

  1. Prepare a portfolio you’ll send before React Native technical interview questions so that the company can clearly view your work and understand your real experience.
  2. You should carefully study the top React Native interview questions in our article. We have worked hard to ensure that React Native interview questions are not a solid set of top phrases, but are divided into three sectors for beginners, mid-level and experienced programmers. You won’t have to scour different sources for React Native answers – they’re all here, and they really work! You will definitely need them! React Native interview is yet to come. Don’t slip!
  3. Even if the company has a different direction in its work, still send your portfolio. Don’t be afraid to pass interviews on React Native developer. Your employer will appreciate your desire to improve. And your technical awareness during the React Native interview process will be an undeniable plus.
  4. An important aspect for a beginner developer will be the charge for success and independence in finding the right solutions.
  5. Upgrade your hard skills with our React Native interview questions and answers. Upgrade your soft skills-communication skills and stress. They will be useful to you in working with the dream React Native experienced team.
  6. If you are a high-level specialist, don’t go through our React Native interview questions and answers for experienced. Do not think that if you are an experienced player, our top list may be useful for you at the interview. Anyway, these questions can easily help you in different hard situations in the tech interview. Pay attention to the details and you will be successful.

How to Prepare for an Interview if You are an Employer?

As a fairly experienced company in the market, we know that even a novice can hide a person with huge potential, who can become a key player in the future. In order not to miss the programmer, we advise all employers to be especially careful when choosing their own person.

Therefore, the employer should also carefully prepare for a technical interview with the candidate. At the first stage of searching for a potential employee, you should pay attention to their portfolio and study the development trends in it. If you see this trace, such a specialist should be considered as a candidate for the position. Also, prepare some React Native interview questions and your desirable answers to check your wishes from the candidates.

We understand that the technical part is very important and during the interview, specialists of different levels will receive different tasks and will be able to answer different levels of questions. You can check your hard skills at the interview. Correctly formulated React Native developer interview questions spend your time and shorten the process.

At the technical React Native interview, you should also pay attention to soft skills. It is prominent how candidates can participate in communication, their knowledge of English, the ability to work in a team and with new tasks.

If a technical specialist is savvy, then pay attention through RN interview questions to his interaction with the team, values, and attitude to work. Sometimes a specialist with mediocre knowledge will be more productive in combination with a great desire to develop and learn than a person of a higher level, focused solely on himself.

The main thing when choosing a candidate is to focus on the person and their abilities. Choosing a new person in the team is responsible, so you need to look at two aspects at the same time – technical and personal, and only then the puzzle can come together in the most favorable balance for you.

Conclusion

It is necessary to prepare for the React Native interview in advance because React Native technical interview questions can scare anyone after all the company you want to job for is at stake. Preparing for interview questions for React Native developers is quite a painstaking process, so the top React Native interview questions we have prepared can simplify this path for you for a while.

Let’s schedule a call to discuss all your needs!

We tried to describe all the aspects that are important for us when choosing the desired candidate and tried to make the process of preparing for the React Native determinant interview as productive as possible. Pre-prepared React Native developer interview questions are good for both employers and candidates. Therefore, you should not be rash about this issue and explore all detail, because a good place in the sun is your responsibility.

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