Today, React is the most popular library for front-end developers. Simply said, learning React improves your development skills, and many organizations consider these skills to be important. React developers should be eager to improve or audit their knowledge of Facebook’s well-known JavaScript Library.

See how you fare against these crucial React developer abilities.

1.Using HTML and CSS

• HTML and CSS are familiar to every front-end developer. Every company needs the capacity to work with and create user interfaces. React developers should be able to do the following at a high level:
• Work with semantic HTML tags and write them.
• Work with CSS selectors and write them.
• Apply a CSS reset.
• Recognize the box model and how to return to border-box modell.
• Flexbox is something you should be aware of.
• Work with and apply responsive web principles, such as how to use media queries correctly.
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2. JSX
You never truly touch HTML correctly in React. You use JSX, a React syntax extension that is truly one of the most impressive components of the ecosystem. Because JSX resembles HTML so closely, it’s sometimes referred to as HTML-flavored JavaScript. What’s great about JSX is that if you know HTML and CSS, you’ll be able to work with it instinctively.

The React.createElement() API is abstracted using JSX. One of the reasons it’s so important to the library—and why the React team chose it in the first place—is that the API would be too difficult to scale without it. One could theoretically use React.createElement() to create a whole application, but this would be no more efficient than using HTML directly. Although it may appear that we’ve taken a step backward by incorporating our Markup into our template logic, all it takes is a few minutes with JSX to fall in love with the look.

3. ES6 + JavaScript Fundamentals
You can’t master React without a good grasp of the JavaScript language’s fundamental ideas, but these ES6 abilities are also required:

Scope and variables
It’s vital to know when and where you can get the data you need. Variables are a built-in feature of JavaScript that allows us to store data in memory and access it later in our apps.

Other than the usual var keyword, ES6 introduced other keywords (such let and const) that can be used to hold variables. You can follow the rule that unless you absolutely require var, use const until your linter tells you otherwise, then fall back to let.

4. Objects and arrays
The React pattern proposes that your view is a function of your state. That’s v = f(s) in arithmetic terms, and it’s something you should keep in mind while you brush up on your library basics.

Data that we wish to present to users or elements in memory that we can access to allow our users to interact with our data are referred to as state. All of the data that we provide is stored on an object called state, and we can access it via attributes on that object. The word React comes from the fact that the view updates as the state changes (v = f(s);). As a result, your view “reacts” to changes in your state object.

You should review how to mutate objects and change the values of their properties. Don’t worry; React takes care of the mechanism with a handy function called setState(), which you can use to your benefit.

Methods that use arrays
It’s one thing to be able to store data in arrays and objects and access it later. It’s another thing entirely to be able to appropriately manipulate that data. Every developer’s toolset should include the built-in JavaScript array functions. For optimum impact, concentrate on.map,.filter and. reduce.

Arrow functions and functions
Explaining functions and arrow functions, is one of the most common react js interview questions, every component you create in React is a function in one manner or another. Remember that under the hood, ‘classes’ are essentially constructor functions. When creating functional or class components, you’re utilizing some form of function, regardless of the syntax you’re using.

Don’t overlook the significance of these principles. There are numerous approaches that lend themselves to functional programming today. It’s like creating a Lego set without instructions when you get the chance to employ JavaScript functions to build up little sections of UI. Each UI element is an encapsulated function that contains the state data, the elements themselves, and the formal component logic you’ll need to use that logic. Each piece is a Lego brick, and it’s up to you to connect them all.

Cross Platforms
Cross-platform software (also known as multi-platform software or platform-independent software) is computer software that works on a variety of systems. Software written in an interpreted language or pre-compiled portable bytecode for which the interpreters or run-time packages are common or standard components of all platforms can be divided into two types: one that requires individual building or compilation for each platform it supports, and the other that can be run directly on any platform without special preparation, such as software written in an interpreted language or pre-compiled portable bytecode for which the interpreters or run-time packages are common or standard components of all platforms. For example, a cross platform might be Reactnative and Flutter. (see differences between React Native vs Flutter)

5. Manipulation of the DOM and event handlers
Manipulation of the DOM elements is uncommon in React. Remember that we now have access to the JSX abstraction. In React, the native event object that you obtain from normal DOM interaction is wrapped up in a class called SyntheticEvent. Ensure that you can connect several types of events to HTML elements, such as onclicks, onchange, and mouseenter, among others.

The keyword “this”
One of the most generally misunderstood JavaScript features is the ‘this’ keyword. Consider ‘this’ as a pointer to a specific object. You can, for example, use the ‘this’ keyword to refer to an object without having to provide its name.

Callback functions and higher order functions
The input/output model of functional programming is based on the idea that functions can be passed around as arguments (in the case of high order functions and callbacks).

Handlers are passed around everywhere in React. The handlers you pass around are often in the form of methods chained onto an object and accessed as properties, which will be bound up in the prototype chain. However, there are times when you’ll need to go outside of the React component paradigm or design a few different sorts of components that overlap in functionality. Advanced React patterns are generally referred to as such, and they’re making their way into the realm of better/common practices. As you scale using React, you’ll be pushed to be more original and creative.



6. Object formation and prototypal inheritance
In many ways, React lends itself to a functional programming paradigm. You, on the other hand, work in the world of classes, and hence in the domain of object creation. You’ll know everything you need to know about inheritance in JavaScript if you understand the basics of how the prototype chain works. Remember that JavaScript doesn’t have any traditional classes. In JavaScript, the class keyword is essentially syntactic sugar on top of the object prototype chain.

The keyword ‘class’
Classes in JavaScript aren’t the same as classes in traditional programming. You construct classes that include your template logic, formal JavaScript logic, and even component styles. These components are the foundation of any React application, and there are only two ways to write them: as a function or as a class.

Check your knowledge of classes by answering the following question: How can I build up methods on a class?

• What’s the best way to connect those methods?
• How can I get access to the constructor’s properties?
• What is the best way to make things that are considered “children” of parent objects?

7. Use Git

• For storing projects on solutions like GitHub, Bitbucket, and GitLab, Git is a must-have in every developer’s toolkit. The following are skills that should be part of your day-to-day routine:
• Adding, committing, pushing, and pulling changes
• Strategies for branching and merging
• Dealing with merge conflicts

Node + Node.js
Many people may be surprised by Node. To be a client-side React developer, why would you need to know how to work with Node? While you may use React on any HTML page, there will be a plethora of different packages available to let you extend the React framework.

The npm registry is critical for React developers to understand. This is the location where software engineers can obtain software to aid in the development of software. That may sound amusing, but that is exactly what npm is: a cloud storage service for packages known as dependencies.

npm vs. yarn

Yarn is a package manager that uses the npm registry as its backend. Yarn helps you get the most out of your npm workflows. Today, Yarn and npm compete in certain ways, but Yarn’s objective has been to fix many of the problems that are common in the Node/npm ecosystem. npm has been doing everything it can to follow the patterns and practices that Yarn presents.