What is React js?

React (sometimes React.js or ReactJS) is the most popular open-source JavaScript library for developing user interfaces. It can be categorized as “V” in the MVC (Model-View-Controller) architectural pattern.

React offers a great answer to user input using a new method for rendering websites.

Facebook developed the components of this tool. It was launched as an open-source JavaScript tool in 2013. React is currently outperforming its significant competitors like Angular and Bootstrap, the two best-selling JavaScript libraries of their time.

According to The State of JS 2019 survey, which over 20,000 developers attended, React leads in the category “Front-end frameworks and libraries.” 71% of respondents said they have used this library and will use it in the future.

How does ReactJS work?

You might be surprised if we say that you can write HTML code in JavaScript. But this is how React works.

You can create a Dom node in React through the createElement function. For example:

As you may have noticed, the syntax in HTML code is very similar to XML components. However, instead of the traditional DOM class, React uses className.

JSX tags have name, descendants and attributes. The quotes in JSX attributes mean strings. This element is similar to JavaScript.

In addition, you must enclose numeric values ​​and expressions in curly braces.

The above example illustrates the syntax well in React, since the tool uses the JSX extension. Basically, it is a combination of HTML and JavaScript.

Here’s an example of React written using JSX:

To get you started, here are some notes regarding the HTML tags above:

  • <MyCounter> has a count attribute that accepts a numeric expression as a value.
  • GameScores is an object literal that has two pairs of values ​​and properties.
  • <DashboardUnit> is an XML block that is rendered on the page.
  • Scores = {GameScores}: The Scores attribute gets its value from the GameScores object defined above.

Most of React is written using JSX (JavaScript XML) rather than standard JavaScript (JS). It is important to note here that this is done in order to simplify the process of creating React components as much as possible.

You can create a React component with standard JavaScript, but we guarantee it will be super messy.

Also, the idea behind JSX in React was that Facebook (as the original developer) wanted to create one specific type of syntax extension with a clear and unambiguous configuration.

When to use React JS?

React is not a framework, so it is not designed exclusively for the web. It is used for rendering and in conjunction with other libraries.

We, at Sannacode, use React Native to build mobile apps; We use React 360 in cases for creating virtual reality applications; besides, there are other options.

Sannacode developers use React in tandem with ReactDOM to build web applications. React, and ReactDOM are often discussed in the same space and are used to solve the same problems as other real web development frameworks. When we refer to React as a “framework,” we mean this colloquial understanding.

The main goal of React is to minimize errors that occur when developing user interfaces. This is achieved through the use of components — stand-alone logical pieces of code that describe part of the user interface. And already these components are combined to create a complete user interface. React abstracts most of the rendering work, leaving you free to focus on design.

React does not enforce strict rules regarding coding conventions or file organization. This allows teams to agree on what works best for them and structure the React project accordingly. React can be responsible for a single button, multiple parts, or the entire user interface of an application.


Hopefully this article has given you some insight into what React is and how it actually works. And at the end of all this, we want to highlight a few main points on the topic:

  • React was created by Facebook.
  • It is used by many major brands and companies around the world.
  • React is a JavaScript library. However, it can also be categorized as a framework.
  • This framework cannot work alone, you need additional elements for purposes such as routing, control, etc.
  • React uses virtual DOM to provide the best optimization for your page.
  • This framework is easy to use and SEO friendly.
  • Supports component reuse.
  • Uses the JSX extension, which is essentially a mix of HTML and JavaScript.
  • React uses JSX to make it easier to create components, not because it performs better.

If you need help developing a user interface with React JS, you can turn to the Sannacode team for a free consultation or help with project implementation.

We’re a full-cycle web and mobile development company with Agile approach and expertise that helps to solve your business’s challenges.