Learn the Fundamentals of React JS: A Guide for Beginners

If you are keen on pursuing your career as a web developer and just getting started, now is the perfect time to figure out the skills you need. Since you will make a living out of developing websites, it is mandatory to learn coding languages like HTML, CSS, and JavaScript.

If you have been through job listings, the one buzzy skill that often pops up from almost every recruiter is React JS. You might have several questions revolving in your mind regarding React; this article is for you.

This guide is far from comprehensive for beginners but will give an in-depth introduction to this valuable web developer tool.

What is React JS?

React is basically an open-source, front-end, JavaScript library exclusively used to build user interfaces, including on-screen menus, search bars, buttons, etc. Anything that users interact with on a website or application can be termed as UI (User Interface).

Jordan Walke, the mastermind behind React, worked as a software engineer for more than a decade at Facebook. He developed React specifically to enhance UI elements, and hence it focuses on being fast, scalable, and minimalistic. Before diving deep into this highly sought after skill, let’s take a step back and get started from rock bottom.

ReactJS is a renowned JavaScript used in web development as it aids in building interactive elements on a website or application. If you are a beginner, we will take things from the origin.

To put it in simple words, JavaScript is a primary coding language in this niche that is predominantly used for adding animated and interactive features to websites and applications.

Its basic structures are created by popular languages like HTML and CSS. Since the scripting language is used to create and control dynamic web content, website visitors need not manually refresh a web page.

Where does React fit in with JavaScript?

JavaScript plays a crucial role in the development of websites and applications. Although incorporating JavaScript makes things more comfortable, it can get annoying as well.

As there are times when JavaScript performs repetitive functions, it can lead to loops. This is where JavaScript libraries take the lead as it eliminates the need for re-coding work.

So what does it have to do with React? React JS belongs to a plethora of JS libraries in the market, and it is unlike the other run-of-the-mill functions. Apart from providing reusable React library code to save development time and minimize the chances of coding errors, it also comes loaded with two key features that add appeal to the developers. They are:

• JSX
• Virtual DOM

JSX:

HTML documents are the heart of any website and web browsers installed on various devices will read these documents while accessing them. To ease things, these browsers create a virtual representational tree of the web page arrangement.

The API is known as the Document Object Model, and it defines the way a document is accessed and manipulated. The Javascript eXtension (JSX) is a React extension that eases the pain for developers as it is supported by almost every modern web browser.

JSX is not just about enhancing the convenience on an overall level, but it also adds for significant improvement in sites and paves the way for efficiency in development.

Virtual DOM:

Things can be different if you don’t use ReactJS as your website will solely rely on HTML to update its DOM. This strategy will not work for dynamic websites as the user interaction will be relatively high, and complications can arise.

However, if a developer incorporates JSX to manipulate and update the DOM, ReactJS will automatically create a Virtual DOM. As the name suggests, it creates a virtual environment where the developers can preview DOM operations and optimize them accordingly.

With its flexibility options, the developers can bring down the overall loading time of a website/application. A selective update strategy can seamlessly deal with dynamic websites and add up to significant value to your platform.

Now that you have a basic idea of ReactJS, let's dive into the components that go into it.

Components of ReactJS:

Components can be referred to as the building block of every React application. To add more value, they are dynamic in nature, and so they can either be used on their own or can be coupled with various other components to develop even larger components.

To break it down further, there are two types of React components:

• Functional components
• Class-based components

Functional components are the simpler of the two types, and their purpose is elementary. It will not be fully aware of its state and merely receives information to turn it into JSX. These components are also known as presentational components, and they significantly focus on altering the UI.

Class-based components are contradictory to the former as it demands to be aware of what the user is doing. In this case, the component needs to be able to send a response to the user in some way every time they are clicked. There are multiple lifecycle methods that will fire at various points between the instantiation and rendering process.

State:

The state is referred to as the most complicated concept in React. However, as a ReactJS developer, you must understand it clearly in order to bring out the full potential of React.

To put it in simpler terms, State is a JavaScript object that continually reacts to and records every user activity on the platform. Since every class-based component of a ReactJS project will have its own state object, every change made to its state will reflect on all of its children.

The process of setting an initial state in the component’s constructor method is also known as instantiation. The JS project snippet given below illustrates that the app component is class-based and so you need to set this.state equal to an object.

class App extends React.Component{
  constructor(props){
    super(props)
    this.state={
      photos: [],
      term: ''
    }
  }

If you need to update a user's interaction with a component on your web page, you must use a different syntax. For example:

this.setState({ term: 'sunsets'})

In order to master the usage of components in your application, you need to begin with assessing the components that rely on the dynamic data.

Since it will undergo several changes over time, you should assign a component that has a state as the parent of every component. As the child components will undergo the same changes, it can have an adverse effect on your ReactJS project.

Props:

Now that you are well aware of the fact that whenever a component’s state undergoes changes, the results are reflected in its child components as well. The prevailing question in every ReactJS developer’s mind is why it is crucial for a component’s children to re-render every time the parent component’s state gets altered.

Props are nothing but objects that will be assigned to every component by its parent. It will contain all relevant information on the respective components. Draw a mental picture of a waterfall and visualize the state as the source of it. In that case, props will be the water that flows downwards.

Since React is a component-based library that segments the UI into little reusable pieces, those components need to communicate with each other if the necessity arises. Props can be used to pass data between them. It is a unique keyword, and it follows a unidirectional flow.

As the data will be in read-only format, the child components cannot be changed in any way. Here is a project snippet from ReactJS where we have established the parent component and included another child component in it.

The ChildComponent for the snippet mentioned above will be as follows:

Benefits of integrating ReactJS into a website:

The integration of ReactJS into a website makes things more comfortable for the developers to seamlessly manipulate and define every component in it up to the root level. Having such an easy-to-follow and comprehensive system drives the platform towards growth.

There will be no room for nerve-racking glitches and slow performance as the system can be maintained easily.

With so many options in the market, integrating a revolutionary tool like ReactJS can slingshot your popularity to a global audience.

Bottom line:

As there is an increase in the number of websites and applications that carry high-volume data in the market, the impact can also be crucial. Incorporating ReactJS is vital to ensure that businesses do not fall into a pond of stress in critical situations. With the numerous advantages of ReactJs, there is a massive requirement for professionals who have perfected their craft.