What is React.js?

The basics

React is a widely-known and popular open-source library for JavaScript built with the intention of creating user interfaces for single-page applications in mind. As such, React is in command of handling the view layer for mobile and web applications, however, it can be also used to create UI components that are reusable.

Thanks to its features, React allows programmers to develop complex web applications with the ability to change data without the need for reloading the page itself. This main principle allows React-based web applications to be fast, simple and easily scalable. React acts only on the user interface side of the web application corresponding to the view in the MVC (Model-View-Controller) template. As such, React can be used with other Frameworks in MVS like Angular JS. It can be also compatible with other JS libraries as well.

Main features

We’ve already mentioned that React can easily allow data changes without the need for reloading making applications fast, scalable, and simple. In this section, we’re going to cover the other important features that make React so immensely popular among the developer community.

1. JSX (JavaScript XML)

In every basic website or web application, the heart that “beats” is a pile of HTML documents. Browsers read these documents and then they display them on your device as web pages as you know them.

During the reading process, the same browsers create a Document Object Model, which is basically a map of the requested web page’s arrangement. In order to improve user experience on the website, developers usually add dynamic content to them, by modifying the Document Object Model with JavaScript and other languages.

This is where JSX comes in for ReactJs. It’s an extension (called JavaScript eXtension), that allows developers to tweak their DOM easily by using basic HTML-style code. Another important thing to mention here is the fact that React supports all modern browsers across the board, making JSX compatible with any browser you may intend to work with. Apart from that, using JSX for DOM updating can improve site performance and development efficiency.

2. Virtual DOM

Without React and JSX, websites usually use HTML for DOM updates (in simpler terms, these updates are the situations when things “change”, on the screen without the need of manually refreshing the screen).

This isn’t really a problem when we are working with simple, mostly static sites. However, in the case of dynamic websites, with constant user interaction, using basic HTML for updates can become a problem, mainly because the DOM needs to reload most times when the user clicks on something that calls for a refresh.

With JSX, developers can manipulate and update website DOMs, because React creates the Virtual DOM. It is basically a copy of the website’s original DOM, and React uses the virtual copy to see what parts of the actual DOM need changing when users click something on the site.

Here’s a simple example. Let’s say, a user comments on a blog post and clicks the “leave a comment” button. When this happens without React, the DOM in its entirety would have to be refreshed to showcase the change – a process that takes up time. With React, the framework simply scans the Virtual DOM and identifies the requested changes (adding a comment) and updates only that specific section in the original DOM.

This selective updating approach makes web applications more efficient since it takes less loading time and computing power. It’s true that for a simple blog comment this wouldn’t mean much on a mostly static site, but when we’re talking about websites that are heavily modified with dynamic features, the Virtual DOM makes a significant difference.

3. React native libraries

React also uses native libraries that nave been announced back in 2015 by Facebook. Native options provide well-known React architecture for native apps like Android, iOS, and UPD. React Native, a mobile application-creating framework uses only JavaScript and the same principles as React, allowing developers to utilize or include rich UI features and handy components, but uses the same fundamental UI building principles as other iOS or Android applications. Besides, it also allows components written in Java, Swift, or Objective-C.

4. Single-way data flow

One of React’s main features is that a set of immutable values are passed as properties in its HTML tags to the components renderer. The component can’t modify the properties directly, instead, it can use a call back function that enables developers to do modifications. This principle is called the “properties flow down, actions flow up” procedure.

The React ecosystem

If you’re new to web development, you can easily get confused regarding React since programmers often refer to ReactJS as a JavaScript library or/and as a JavaScript framework.

Some developers see it as a JavaScript library and not as a true framework, because in the case of a library, the developer uses library code in individual instances that call for it. In the case of frameworks (like Angular, for example), they create a specific scaffolding that arranges the web application giving dedicated areas for codes to be plugged-in.

To make this a bit simpler, think about JavaScript library codes as house decorations or furniture you’d put in your house (website) you’ve already built. And the framework is the template model you used to build your house with.

Other developers like to refer to React as a full-blown framework because of its robust ecosystem and rich extension options. Also, when programmers choose React to build their web application user interfaces, they also have access to an array of features:

• Code snippets components (building blocks for creating specific parts of the UI)
• JSX for direct DOM manipulation
• The Virtual DOM that allows for dramatic improvements on dynamic-heavy applications.

Apart from that, React is a free, open-source project. This means that any developer can download and modify the source code. This is also a huge help if you are facing a specific problem with a specific UI function since chances are that someone has already created a library that resolves your issues. You can also utilize everything the huge community has, not just for specific individual features but also for entire templates if you wish to build a UI from the ground up.

React and developers – why should one choose React?

As with every framework and other software, developers would often ask why they should choose this specific one over another. There are literally countless open-source platforms when it comes to front-end web app development, and all of them offer a great feature that makes the development process easier, the end product sleek, and user-experience great.

Even in such stiff competition, React, one of the most popular JS libraries can still offer a few outstand-ing features that make it a mainstay in most developer’s arsenal. Here are some of the main advantages of using React:

1. Simple to use and to learn

This is a huge selling point for most software. Grasping the basics out of the box lets developers jump into projects much faster, making the specific software/framework/library not just a handy, but a cost-effective tool too.

React’s component-based approach and the use of simple JavaScript make it simple to build professional mobile and web applications a breeze. JSX, the special syntax allows developers to dwell deeper into the land of HTML and JavaScript crossovers, enabling them to even further improve applications.

React can be easily grasped by everyone with basic programming knowledge and experience. It doesn’t require the developer to learn “Domain-specific Languages”, which can sometimes eat up too much time unnecessarily, especially from a material standpoint. React, on the other hand, only requires basic CSS and HTML knowledge.

2. Native approach

As mentioned before, with React Native, developers can simply create great mobile apps dedicated to native platforms, with extensively reusable codes.

3. Building data

The one-way data building feature and the entire architecture (also called as Flux) creates an efficient data flow to components through the dispatcher, a single control point. With this feature, debugging components of large apps is a lot easier.

4. Performance and testing

We’ve already discussed the benefits of the Virtual DOM. This feature can significantly improve site performance, especially with larger, dynamic user interfaces.

On the other hand, React itself does not have any out-of-the-box container for sorting out dependency issues. However, to overcome this, developers can use an array of different modules, like Require JS, EcmaScript 6 and Browserify, which when used via Babel, inject dependencies automatically.

Testing-wise, React applications are great because they are simple to test, as React lets developers take a look at the output, along with the triggered actions, events, functions… This feature allows for simple and precise troubleshooting.

5. Declarativity

This means that the React code focuses more on what is displayed than the actual steps that lead to it. This method first and foremost means improved developer-experience which later on translates into a better user experience.

Sadly, developer-experience is oftentimes an overlooked feature, even though it should be prioritized by software development companies. Why? Firstly, if the software is hard to work with, chances are, developers will abandon it sooner or later and move on to a different platform. Secondly, if enough is invested in creating a smooth and great development environment, there’s a better chance of creating a better experience for the end-user as well. Also, when the software is open-source, fond developers can further enrich its features, leading to a robust “all-in-one” software that can tackle most projects with ease.

6. Component-based approach

Apps are being constructed in React by building blocks – components responsible for UI functions, network communications, and even more complex functions like managing the stage. This specific approach makes design system implementation simple and streamlined for developers.

7. Minimalism

React sports a minimalist approach. For starters, it’s small and can be downloaded quickly. Configuration is also simple and the code-splitting feature (we’ve discussed it before) makes it a breeze when it comes to user experience, especially with larger projects. Improved loading time and overall performance can also help marketing efforts (SEO) because Google tends to promote short-loading time websites.

8. Flexibility

When business owners consult with developers, they usually want a website that is overall easy to use and lasting. Because of this, developers most often than not use software that is already popular with extensive features and options. Expanding libraries and further software development will also mean that on-the-fly tweaking will also be easier and extensive libraries from the developer community will allow programmers to create breathtaking interfaces.

9. Backward compatibility

This is also a crucial feature when it comes to choosing specific software. Being able to update or to work with older versions of software can save a not just time but also a lot of headaches for developers. There aren’t that many frameworks or languages that offer total backward compatibility, but React does.

Initially, this was more because of Facebook’s internal team rather than for the community. Some Facebook apps still run on initial React versions and overhauling the entire website would probably be a huge and daunting endeavor not just for the developer team, but for the entire company.

In other circumstances, it’s mostly too expensive for software developers to provide total backward compatibility for older or outdated versions.

Putting it all together

As stated before, ReactJs is a JavaScript library/framework used for creating smooth and dynamic user interfaces, developed by Facebook in 2011.

Since React’s initial release, it has become one of the most prominent pieces of front-end interface software on the market.

For most front-end developers, it can have every single tool they need to create a dynamic-heavy user interface that’s fast-loading and well-performing. It’s a robust software that’s easy to learn and work with, drastically improving designer-experience, and a crucial factor for overall great user-experience. Virtual DOM gives the option of swiftly handling user requests without frequent refreshes making it ideal for improving SEO as well.

It’s backward compatible meaning that older versions won’t cause unnecessary headaches.

However, there’s no perfect software and React is no exception. As possible drawbacks, some developers point out that while understanding the core mechanics behind React is fairly simple for newcomers, they can still face obstacles when they need it to integrate it into an MVC framework since React itself isn’t one. Others said that they dislike JSX’s documentation, stating that manuals are hard to understand for newcomers. Other times, even the large-sized library can cause different problems for developers.

Albeit there clearly are some drawbacks to ReactJS, it’s still one of the best and safest software for developers to exploit, especially if they wish to create a web application with long-term support, great speed, and dynamic features.