1. What is React JS?

Let us give you a brief introduction to React. In the world of web development, React is the most in-demand JavaScript library available. There are quite a few benefits of choosing React over other frameworks such as Angular.js. The React js library was specifically created by the Facebook software engineer Jordan Walker to build fast and interactive UIs for web and mobile applications. This open-source front-end library is component-based and is responsible purely for the view layer of the application. The view layer is the one that is responsible for the look and feel of the app in the MVC architecture. 

React js is highly sought after for its versatility and ability to simplify the building of apps and websites alongside creating UI test cases and reusing existing website code to improve overall UI and web application performance.

 2. Why is React so popular in the development of front-end web applications?

The popularity of React js overshadows all other front-end development frameworks of today. Why is React so widespread?

• React makes it convenient to generate dynamic applications since it requires less amount of coding. Unlike JavaScript that deals with complex coding, React offers better functionality. 

• Unlike the more conventional web applications where you have to spend time updating every single component, React js can generate web applications faster using VirtualDOM. The VirtualDOM compares the previous states of the components’ and only updates the items in the Real DOM that were changed.

• Applications built on React use components as their base using multiple components within any individual application. Each component carries its logic and controls with them, which can be reused in different parts of the application, thereby saving a chunk of time in the application’s development process.

• React uses unidirectional data flow where the developers use parent components for nesting the child components within them to make the process of debugging errors more convenient as it enables the developer to identify the precise location of the problem at any moment.

• React is relatively easy to grasp as it is predominantly a mix of concepts from HTML and JavaScript with a few other attributes, and it only requires that you spend some time understanding its library.

• React can be used to develop mobile and web apps with the React Native framework handling the creation of its exquisite mobile applications.

• React js possesses a dedicated set of tools that enables convenient debugging. For, e.g. the chrome extension released by Facebook that’s used for debugging React applications.

3. Advantages of using React

• Ability to write components using JSX

By simply using JSX, a syntax extension for JavaScript, developers build React components considered the building blocks of React applications. The use of JSX enables the developers to tap into HTML code, making it dynamic, thereby ensures it is easy and convenient to alter the user interface.

• Increases productivity by reusing  components

React’s components are reusable, which means that it is beneficial towards managing consistent structures throughout the web application. Furthermore, it offers fast rendering speeds.

• Stability over time

The backwards-compatible updates of React make it advantageous for developers as they do not have to update their codebase each time React releases a new version.

• Better performance via the VirtualDOM 

VirtualDom enables React to conduct computations before rendering an updated layout, increasing the speed of performance within the application.

4. Who is a React developer?

In simple terms, React developers are front-end developer highly experienced in using React and React Native. React developers create delightful user interfaces by applying their knowledge of JavaScript. If full-time React developers have engaged in learning the MERN stack, they’re also proficient in Express, MongoDB and Node.js. Although most organizations today do not require knowledge of the MERN stack, learning this popular tech stack is almost a right of passage for developers. In addition to their tech stack, React developers will be experienced in varying other capacities based on the organizations they’ve worked for and the tasks they’ve engaged in.

5. Reasons and benefits of  hiring a React developer

• Only a few developers are required

Using react native is very cost-efficient since almost 90% of the codebase can be used throughout the platforms without having expert knowledge of the different programming languages.

• It is time-efficient

React lowers the amount of time required to generate innovative products. The open-source technology strengthens the developer community, and in turn, they receive better feedback and improved code. Additionally, the availability of hot reloading provides instant modifications to the code, enabling the app to run efficiently even as the UI is being edited.

• It enhances performance

React enables developers to seamlessly convert web applications to mobile versions without consuming much time. As developers are no longer required to write code from scratch, it saves companies valuable resources that would otherwise be spent on app development. In addition, React Native can achieve 60fps, thereby delivering better application performance due to the UI running more smoothly.

• It generates functionality and agility

Developers build applications with diverse features through React using existing codes themselves. They can be as agile as needed while generating their apps on a fully functional back-end. Since React uses the programming language JavaScript, it can work across all platforms, making building through React extremely functional for the developers.

6.  How to hire a React developer?  

React is one of the more popular frameworks around these days, and as such, it is not too difficult to find yourself React js developers. However, what is difficult is to find is a ‘great’ React developer.

The reason for this is that any developer who understands the basic concepts of React can start building simple applications straight away. This may be an advantage for those who want to have some background knowledge, but when looking for a candidate who can develop a complex application, this is not the kind of skill set you’re looking for.

There are plenty of options out there through freelance platforms and online marketplaces when it comes to hiring developers. But how do you make the right hire? What are the qualities you should look for in a React developer?

Hiring a developer is no easy task as you need to focus on the technical aspects. To make a successful hire, you’re required to have some form of knowledge on software development in general. 

We have made things easier for you by providing an outline on how to find React.js developers suitable for your organization.

7. What to look for in a React developer  

The React js developer you’re looking for is most likely a full-stack developer who is either capable of building the system you require from scratch, or he/she should have a good understanding of the tech stack you are currently in need of. 

At a high level, React developers should be able to:

• Work with HTML and CSS
• Have a high-level proficiency in JavaScript and ES6 with a good understanding of Redux and Hooks for state management
• Understanding of Node.js and NPM for third-party integrations
• Knows MVC design patterns and be able to set up a database and interact with its APIs
• Be capable of writing clean code
• Be able to learn new technologies and read their documentation to build out new functionality and features.

8. Cost of hiring a React developer

• Average React.JS Developer annual salaries in the US range between $90,000 to $140,000
• Average Hourly Rates of React.JS Developer salaries in the US range between $56 to $76

Since hiring developers from the US is pretty expensive, most businesses opt for overseas talent. Online marketplaces make it very convenient to tap into the global market to hire highly qualified remote developers from across the world at reasonable prices.

Here’s a list of Average React.JS Developer Salaries & Hourly Rates from around the world:

table

9. Why hire a React developer with CloudDevs

CloudDevs offers highly vetted, elite Latin American remote developers at $40-$50 per hour.

When you hire through CloudDevs, you have the assurance that a suitable talent from our pool of extensively vetted React JS developers that meets all your requirements is assigned to your project in under 24 hours. 

Each client is matched to the talent based on their location’s time zone to ensure smooth communication processes. Additionally, CloudDevs offers a 14-day risk-free guarantee in case the client is not happy with the outcome.

10. Relevant React tools 

There are a series of extensions, libraries, and frameworks referred to as React tools designed to simplify the development through React. React developers use various utilities for testing, debugging, and code generating to create more stable and effective code quickly. 

Most React tools can be installed as extensions on browsers making them easy to access for React developers. 

React tools can be utilized during the software testing stage to spot problems and enable developers to solve them fast before the final testing takes place.

11. Some React resources  

• https://github.com/enaqx/awesome-react
• https://reactjs.org/community/courses.html
• https://dev.to/hulyakarakaya/ultimate-react-resources-obl
• https://geekflare.com/reactjs-learning-resources/

12.  Companies who use React :

• Airbnb
• Uber
• Netflix  
• Instagram
• Pinterest
• Medium
• Facebook
• New York Times

13. React alternatives and comparisons:

• AngularJS – Considered the best alternative to React JS for building highly dynamic web, desktop and mobile applications, Angular is an open-source front-end JS framework used to structure and simplify JavaScript Code. It enforces dynamic restructuring of pages by using SPA to rewrite only the current page instead of loading entirely new pages from the server. 
• NativeScript  – As a tool in cross-platform mobile development, NativeScript allows developers to build iOS, Android and Windows-powered apps while sharing the codes across the platforms. 
• Vue.JS – Used to create web UIs Vue is a progressive JavaScript framework entirely created and maintained by the community. Flexible and developer-friendly, Vue is considered faster than React when it comes to performance. Similar to React, Vue is known to be quite easy for developers to grasp.
• Ember.js – While React is a JavaScript library that allows developers to create user interfaces easily, Ember offers an open-source JavaScript framework that enables developers to build scalable single-page web applications.
• jQuery – Unlike React, jQuery interacts with the DOM directly, which means it’s much slower than React.
• Backbone JS – Similar to React JS, Backbone provides a structure to JavaScript-heavy applications by using value-binding and custom events, declarative event handling and collections of API with various functionalities all combining with existing apps over a RESTful JSON interface.

14. Top interview questions to ask when hiring React developer

Q1. How is React different from other JavaScript frameworks out there?

• What React JS Inherits – React, uses JSX instead of regularly using JavaScript for templating. JSX is basic JavaScript that facilitates HTML quoting and uses the syntax of this HTML tag to make subcomponents
• Single Movement of Data – Through React, the component’s renderer has transferred a collection of immutable values as property in its HTML tags. Components cannot alter any property directly but can transfer a call back feature with the aid of which we can make changes.
• React Native – ReactJS comes with native libraries allowing developers to build diverse applications with required front-end functionality. It has a collection of modular UI elements both for Android devices and for iOS. Using React Native you can use the native look and feel to develop any mobile application.
• Virtual Document Object Model – React’s unique Virtual Document Object-Model allows the data structure to be created for various functional operations. It deals with shifts in the calculation as well as the software upgrade. This makes programming for programs with required logical operations simpler for programmers. React library allows for every shift a tab.

Q2. What are the benefits of ReactJS over others

• Simplification – ReactJS is easier to grasp automatically. The component-based approach, well-defined lifecycle, and use of plain JavaScript make Reacting very easy to learn, build and support professional web and mobile apps. React uses a special JSX syntax that lets you combine HTML with JavaScript. This is not a requirement; but JSX is much easier to use, developers can still write in plain JavaScript.
• Reusable elements – The technology used to be far more complicated than that, but ReactJS provides us with the ability to do just the same. Each React project is constructed using the so-called reusable elements. This means that by calling from other components, each element of the interface that you have already built can be used anywhere in your project.
• Works well with SEO – The big drawback of many JavaScript applications is that they’re not accessible to the search engine. In this region, however, some have made significant improvements, but are not very helpful to complement SEO practices. Surprisingly, ReactJS is working with SEO to perfection. You can run ReactJS on the server, and the virtual DOM will be rendered as a regular web page to the browser, with no other practices required.
• Performance – React does not deliver the definition of an interconnected dependence frame. You can use Browserify, Require JS, EcmaScript 6 modules that can be used to insert dependencies automatically through Babel, ReactJS-di.
• Handy support – Additionally, React JS has gained credibility because of the availability of a convenient set of tools, which allows the developers ‘ job even simpler. The React Developer Tools are developed as an enhancement of Chrome tech. You can have a test on the hierarchies of reactive elements as well as the present state and props of the system.
• Easier to create interactive web apps – Specifically designing a dynamic web application with clumsy HTML strings was a troublesome affair, as complicated coding was needed. React JS, however, has solved that problem. This uses the JSX, a special syntax that enables HTML quotes and HTML tag syntax used to make different subcomponents.
• Access to developers – React JS is one of the developer community’s most common frameworks and is a framework that many developers choose to use. It will thus be easier for you to find a developer for React JS. Alternatively, training a developer with React JS, which has basic knowledge of JavaScript and front-end development, is easier.

Q3. What can you tell me about JSX?

• JSX stands for JavaScript XML. It allows us to write HTML in React. JSX also makes it easier to write and add HTML in React.
• JSX allows us to write HTML elements in JavaScript and place them in the DOM without any createElement()  and/or appendChild() methods.
• It converts HTML tags into react elements.

Example 1 [using JSX]

const myelement = <h1>I Love JSX!</h1>;
ReactDOM.render(myelement, document.getElementById('root'));

Q4. Can you use React without JSX?

You do not have to use JSX. However, JSX makes it easier to write React applications.

Here is the same code as in the above example written without JSX:

Example 2 [without using JSX]

const myelement = React.createElement('h1', {}, 'I do not use JSX!');
ReactDOM.render(myelement, document.getElementById('root'));

In above Example 1, JSX allows the writing of HTML directly within the JavaScript code.

JSX is an extension of the JavaScript language based on ES6, which is translated into regular JavaScript at runtime.

Q5. Can you describe the lifecycle of a React component?

Each component has several “lifecycle methods” that you can override to run code at particular times in the process. This lifecycle diagram is useful in understanding a React component’s lifecycle.

Q6. What are the stateless components of React?

A functional/ stateless component is simply a plain javascript function which takes props as an argument and returns a react element.

<div class="wp-block-codemirror-blocks-code-block code-block"><pre>const MyStatelessComponent = props =&gt; &lt;div&gt;{props.name}&lt;/div&gt;;// without JSX 
const MyStatelessComponent = props =&gt; React.createElement('div', null, props.name);</pre></div>

A stateless component means that you can’t reach this.state inside it. Additionally, it has no lifecycle so you cannot use componentDidMount or other hooks.

Q7. What’s VirtualDOM and how does React use it?

The virtual DOM (VDOM) is a programming concept where the “virtual” representation of a UI is kept in memory and synced with the “real” DOM by a library such as ReactDOM. This process is referred to as reconciliation.

This approach enables the declarative API of React. That is: You instruct React what state you want the UI to be in, and it makes sure the DOM matches that particular state. This abstracts out the attribute manipulation, event handling, and manual DOM updating that you would otherwise have to use in order to build your app.

In the world of React, the term “virtual DOM” is usually associated with React elements as they are the objects representing the user interface. React, however, also uses internal objects named “fibres” to hold additional information about the component tree. They may also be considered a part of “virtual DOM” implementation in React

Q8. How would you use Redux in a React app?

• You can use Redux together with React, or with any other view library. It is tiny (2kB, including dependencies), but has a large ecosystem of addons available.
• Redux is a predictable state container for JavaScript apps.
• Redux Toolkit is the official recommended approach to writing Redux logic. It wraps around the Redux core and contains packages and functions that are essential for building a Redux app. Redux Toolkit simplifies most Redux tasks, prevents common mistakes, and makes it easier to write Redux applications.

Q9. What are the limitations of React?

React Technology accelerates so fast that it cannot make proper documentation of the project. So, the developer tries to write the instruction on its own.

• React focus on the view part of MVC i.e. UI of the web application. So, to overcome these problems, to focus on other development we require other tools.
• React also has a large library.
• Some of the command or syntax has to be part of JavaScript as CONDITIONAL BLOCKS, which are not allowed in the JSX part of the documents.
• HTML attributes names are case insensitive.
• In React, some standard functions will not be able to use the state effectively. Instead, we go for the use of ES6.
• Extension of the files can be emitted only to the JavaScript files so that to ensure that every CSS file is imported in ReactJS.
• Some developers think JSX is a barrier especially for new developers because they have a complaint about the complexity of a learning curve.

Q10. How is React.js different from Angular?

The primary difference between AngularJS and ReactJS lies in the state of its management. AngularJS has data binding bundled in by default, whereas React is generally augmented by Redux to give unidirectional data flow and work with immutable data.

Q11. How can you create an event in React?

import React from 'react';
import ReactDOM from 'react-dom';
function shoot() {
  alert("Great Shot!");
}
const myelement = (
  <button onClick={shoot}>Take the shot!</button>
);
ReactDOM.render(myelement, document.getElementById('root'));

Q12. What is the significance of keys in React?

Keys help React identify which items have changed, which terms are added, or which are removed. Keys should be given to the elements inside the array to give the elements a stable identity.

const numbers = [1, 2, 3, 4, 5];
const listItems = numbers.map((number) =>

 <li key={number.toString()}>
   {number}
  </li>
);

When the state of your component changes, the render function will return a new tree of React elements, different to the previous/current one.

Q13. What is the difference between state and props?

In React components, props are variables passed to it by its parent component. State although is still a variable, it is directly initialized and managed by the component. The state can also be initialized by props.

For eg. a parent component may include a child component by calling:

<ChildComponent />

The parent can pass a prop by using the syntax:

class ChildComponent extends React.Component {
  constructor(props) {
    super(props)
    console.log(props.color)
  }
}

And any other method in this class can reference the props using:

this.props.

Props can be used to set the internal state based on a prop value in the constructor:

class ChildComponent extends React.Component {
  constructor(props) {
    super(props)
    this.state.colorName = props.color
  }
}

The component can also initialize the state without looking at props.

Props should never be changed in a child component, so if there’s something going on that alters some variable, that variable should belong to the component state. In addition, props are used to allow child components to access methods that are defined in parent components. This is a means of centralizing the state management in the parent component and to avoid children having to need their own state.

Most components will simply display some sort of information based on the received props and continue to remain stateless.

Q14. How is React different from Angular?

table

Q15. How would you create Higher-Order Components in React?

A higher-order component (HOC) is an advanced technique in React for reusing component logic. HOCs are not really a part of the React API. They are a pattern that emerges from React’s compositional nature.

Essentially, a higher-order component is a function that takes a component and returns a new component.

const EnhancedComponent = higherOrderComponent(WrappedComponent);

Whereas a component transforms props into UI, a higher-order component transforms a component into another component.

HOCs are common in third-party React libraries, such as Redux’s connect and Relay’s createFragmentContaine

Q16. What is the react context and what problem does it solve?

React Context solves the problem of props drilling. It allows you to share props or state with an indirect child or parent.

Ordinarily, you’d use a state management library like Redux or Mobx, but there may be cases where you don’t want to. Or the data to be passed would be so minute that using a state management library would be over the top.

15. Conclusion

Hiring the best freelance React.js developer is crucial to making your project a success. Making the right hiring decision does not have to be difficult, provided you use a reputable platform that vets their developers and matches you to a talent with experience in the manner of work your project requires. This is precisely what CloudDevs does for you. We have already conducted the vetting process of our talent, thereby eliminating your hassle of interviewing and shortlisting candidates. Additionally, we ensure that all our elite senior developers are personally matched for your requirements to make it a success.