ReactJS In-Depth: Everything You Need to Know

ReactJS is an open source javascript library used to build user interfaces, typically for single page applications.

It enables developers to modify or edit and refresh the page to view the changes without having to restart or reload the page.

React offers the facility of code reusability on multiple platforms. It is fast and scalable.

Most of the large organizations such as Instagram, Netflix, Spotify have opted to use ReactJs. It is the most popular javascript framework with an 87.49% satisfaction rating.

With React we can create:

• Progressive Web Applications
• Scalable Web Applications
• Modern UI/UX
• Reusable Components
• Small to Big-scale Projects

Why should you learn ReactJS

ReactJS is ever growing and the community is also growing quickly. There is no reason to stay back.

I am not going to compare ReactJS with any other frameworks here. They are all excellent in their ways, like how ReactJS is an excellent library for user interface development. Also ReactJS is a base for many other popular frameworks like Gatsby, Remix and Next.

Also Read: Reactjs best practices 2022, code this not that

1) It’s Simple to Learn

React.js builds on your existing knowledge of fundamentals of web development and any developer with even basic knowledge of javascript can build apps in reactjs after just a few days of learning.

2) Strong Community

The ReactJs community is immensely active and will help you in no time if you ever stuck on anything.

3) High Paying Jobs

As reactjs is one of the most popular and loved frameworks, it has a huge job market that is high paying even for junior developers.

Is ReactJs good career

Highly paid and diverse roles. High demand and even diverse roles like stepping into UI engineer or a full stack developer or any domain of web development are open for ReactJs developer. As is evident from above, the salaries are high and the better you become the higher you can earn.

Do we really need to use ReactJs

One of the big problems in the industry is that new developers who start learning Frontend try to learn modern technologies without searching about the needs which caused them to be created.

Difficulties in the development phase play a huge role in creating new technologies. On the Frontend side, ReactJs was created for the same reasons.

As developers, if we want to develop strong skills we need to know the differences between plain javascript and React.

Also Read: Latest JavaScript Features Every Web Developer Should Know

1) How does the webpage actually load

PLAIN JAVASCRIPT

When you’re using plain javascript you will likely already have an initial HTML file that you import your script into and load all your code and logic in that way.

REACTJS

React apps start with a blank HTML page and the initial javascript state is dynamically created based on your declared components and logic. The whole application gets bootstraped into a single root div element.

2) Components to Rescue

PLAIN JAVASCRIPT

Building a complex application with plain javascript is a pain, not only do you need to plan a lot for things to go your way but it becomes really hard to split your code into structures that makes sense.

REACT

React requires you to break your UI into components, which makes your code clean, easy to understand and easily testable. This is huge advantage and will make a big difference in time spent developing and the quality of the outcome.

3) Giving the DOM a break

PLAIN JAVASCRIPT

With plain JS, you usually have to find exact DOM nodes that you want tot update and manually append or remove elements and attributes. This can quickly get messy and result in confusing code.

REACT

React.js will automatically update your UI based on the project structure and changes detected in state eithin your components. React does this by rendering UI elements dynamically using the virtual DOM.

ReactJS Developer Roadmap

Now let’s take a look at the tools and languages you need to know to be a successful react developer.

1) HTML

HTML has a crucial impact on creating web components in react applications.

HTML is used in the .jsx or .tsx files to define our component elements. We can use HTML tags directly inside these components.

2) CSS

Styling is one of the most important things in web development. Especially if you are Frontend developer. You will spend so munch time making perfect stylings. These changes require so munch styling knowledge, there is another language you should learn along with HTML and that is CSS, which is used for styling purposes.

3) JavaScript

Javascript is one of the key languages while learning reactjs, you should learn Javascript as well. Javascript evolves every year and increases its power more than ever.

Except than the creating HTML and CSS we will mostly use JavaScript for writing react code.

4) NPM

NPM is a package manager for the javascript libraries and frameworks.

While you are learning how to start react projects and also creating one you will need to use package manager to install required packages to your local device.

You can search for the packages in the NPM through their website.

Learning npm also will be done along with the projects you make with React.js as well.

5) GIT

In programming, git is one of the most important tools you need to learn to submit your code and work with another developers code.

Related: Get Started with Git and GitHub – With Complete Cheatsheet

6) ReactJS

Learning react will enable you to make faster user interfaces with cleaner code. In this step you will start using your knowledge from the parts described above. Now these languages and tools will be your helpers along the journey of learning reactjs.

While learning react there is very good documentation on the official reactjs website. You can follow the tutorial to learn reactjs.

We are not done yet 🙂

I know the title of this section of article syates react developer roadmap, but after you learn reactjs there are some other libraries we need to use along with reactjs for state management.

7) Redux

After you have gained a basic understanding of using react and feeling comfortable enough to create your own projects there is another topic which will appear in the react development life cycle and that is the state management.

State management is a really important topic in react development. There are many libraries you can use for the state management but i prefer using redux.

After you learn regarding to Redux as well there is another tool which is broadly used in Javascript ecosystem. Last but not least TypeScript.

8) TypeScript

TypeScript is used to use types inside the javascript. For the large-scale applications TypeScript definitely helps a lot along the way.

You should learn and use TypeScript in your projects. It will help you to identify possible issues when you write the code itself. Which will provide you much more time than searching the whole code flow for some bug in the code itself.

9) GraphQL (optional)

GeaphQL is a very powerful tool and it makes queries and requests much easier. When you make a couple of projects with React.js i suggest you to test out making some of the projects with GraphQL as well.

Modern ReactJS Stack for Web Apps

Since the release of React, it has continuously developed a large ecosystem of libraries, frameworks and tools around it that is growing only larger with every year.

Today when making decisions in development, we have to pick the right tools for the job in order to build stable apps and great user experiences.

This section of this article is here to show you a Frontend React Stack and to help you pick modern technologies to build your web apps.

1) ReactJS Framework – Next JS

NextJS is an amazing framework build on top of React, it adds many of the things that React is missing, such as routing, server side rendering and much more.

It even gives you the ability to create API routes to build backend functionality, and has great support for TypeScript.

Alternatives

• Gatsby.js
• Remix

Also Read: Speed Up Your Website With These Simple CSS Tips

2) Component Library – Chakra UI

Chakra UI is a very simple, easy to use and modular component library that gives you everything you need to build amazing UI’s.

Also Read: GitHub Repos That You Won’t Believe Exist

It is fully customizable and compatible with NextJS, Gatsby.js, remix and more.

It also has some awesome integrations ready for you!

Alternatives

• Ant Design
• Mantine

3) State & Data Fetching – React Query

React Query is a super powerful data fencing library that has a lot of great functionalities built-in, such as caching, prefetching pagination and much more.

Using it in combination with the Context API is a great recipe for building performant apps with data that is managed very well.

Alternatives

• Axios
• Redux
• MobX
• Context API

4) Development and Testing

Storybook (Documentation, Development & Testing)

Storybook is an amazing tool used for developing components in isolation, it’s used for building awesome interactive docs, and live testing.

Jest – (Testing / UnitTests)

Jest is the go-to library for testing ReactJs apps, it’s easy to use, beginners friendly and very simple to set up.

8 ReactJS Tips you must know

1) Keep Components Small

To avoid spaghetti code and too much scrolling inside your files, keep your components as small as possible. The smaller the component, the less chances there will be for errors. Small components are easy to handle.

Think about your logic and try to split your app into smaller chunks.

Also Read:

2) Auto Assign Keys to a list of elements

React has a built-in React.Children.toArray() method that handles the keys automatically in your map call.

//Instead of this

{ myList.map(item => <div key={item.id}>Hello</div>) }

//Do this

{ React.Children.toArray(myList.map(item => <div>Hello</div>) }

3) Using Fragment Shorthand

When you need to insert a React fragment, there’s no need to call the entire tag, you can just use the shorthand.

//Instead of this

<React.Fragment>
...
</React.Fragment>

//Do this

<>
......
</>

4) Avoid Overloading JSX

Keep logic out of your JSX and use handlers instead, this will save you from biflg headaches down the road and make your code easier to modify.

//instead of this

<input onClick={(e) => {
//click logic
}}/>

//do this

const clickHandler = (e) => {
  //click logic
}
<input onClick={clickHandler} />

5) Write Better JSX Conditionals

Improve the quality of your code by using short-circuit evaluations instead of a full ternary call.

//instead of this

{ return user.isAdmin ? <AdminComponent /> : null }

{ return ussr.isAdmin && <AdminComponent /> }

6) Destructure your Props

To make things simpler and your code cleaner, user prop destructuring and pass them to your components using the spread operator.

//instead if this

<Profile
  user={user}
  followers={followers}
  posts={posts}
/>

//do this

const props = {user, followers, posts}
<Profile {...props} />

7) Prefer Functional Components

With the introduction of hooks, functional components have become the better way to write react applications.

With hooks inside functional components, you can do anything you were previously able to do using class components, but you can do it in a much simpler way.

8) Creating and Use Custom Hooks

You can use custom hooks created by others or even create your own utilities using react hooks. This will help you avoid code duplication and establish a clean way to add functionalities to your components.

Top 8 ReactJS Interview Questions

1) Differentiate between real DOM and Virtual DOM

REAL DOM	VIRTUAL DOM
It updates slow	It updates fast
Can directly update HTML	Can’t directly update HTML
Creates a new DOM if element updates	Updates the JSX if element updates
DOM manipulation is very expensive	DOM manipulation is very easy

2) What is JSX in ReactJS

JSX is a shorthand for javascript XML. This is a type of file used by React which utilizes the expressiveness of javascript along with HTML like template syntax. This makes the HTML file really easy to understand. This file makes applications robust and boosts its performance.

3) In ReactJS, what do you understand by Virtual DOM

A virtual DOM is a lightweight javascript object which originally is just a copy of the real DOM. It is a node tree that lists the elements, their attributes and content as objects and their properties. React’s render function creates a node tree out of the react components.

It then updates this tree in response to the mutations in the data model which is caused by various actions done by the user or by the system.

4) “In ReactJS, everything is a component.” Explain?

Components are the building blocks of a react application’s UI. These components split up the entire UI into small independent and reusable pieces. Then it renders each of these components independent of each other without affecting the rest of the UI.

Also Read: Scss vs Bootstrap vs Tailwind CSS

5) What is purpose of Render() in ReactJS

Each react component must have a render() mandatorily. It returns a single React element which is the representation of the native DOM component. If more than one HTML element needs to be rendered, then they must be grouped together inside one enclosing tag such as <form>, <group>, <div> etc. This function must be kept pure that is it must return the same result each time it is invoked.

6) How can you embed two or more components into one in ReactJS

class MyComponent extends React.Component{
  render() {
    return (
      <div>
      <h1>Hello</h1>
      <header>
      <div>
    )
  }
}
class Header extends React.Component{
  render() {
    return 
      <h1>Header Component</h1>
  }
}
ReactDOM.render(
  <MyComponent />, document.getElementById('root')
)

7) What is State in ReactJS and how is it used

States are the heart of React components. States are the source of data and must be kept as simple as possible. Basically, states are the objects which determine components rendering and behavior. They are mutable unlike the props and create dynamic and interactive components.

They are accessed via this.state()

8) What is arrow function in ReactJS. How is it used

Arrow functions are more of brief syntax for writing the function expression. They are also called “Fat arrow” (=>) functions. These functions allow us to bund the context of the components properly since in ES6 auto binding is not available by default. Arrow functions are mostly useful while working with the higher order functions.

Top 7 Websites to learn ReactJS

Here is a handpicked list of 7 best websites, where you can learn Reactjs.

1) React (Official Website)

Always learning any kind of programming language of framework from official documentation is a good idea since it was written by the professionals who have created or developed that technology.

2) Udemy

This is one of the best platforms that i suggest people take a look at and learn from their thousands of free online courses in different industries and technologies and React is one of them.

3) Coursera

Coursera is another great platform that offers online courses, specialization, online degrees and professional courses created by top tech companies like Google, Amazon, Microsoft etc.

4) FreeCodeCamp

FreeCodeCamp is a non-profit organization that has more than six thousand tutorials about technology and programming on their website and YouTube channels.

5) AlterClass

this is another good website to learn ReactJs online. It has one of the best paid online React courses which covers everything you need to know to become a React expert.

6) Pluralsight

When it comes to learning to React on Pluralsight, Building apps with React.js and Redux is the best course intended to be for intermediate people who have some basic understanding.

7) Scrimba

This is another great resource to learn Reactjs for free in 2022. This ultimate React 101 is an interactive course to learn reactjs and a perfect starting point for any react beginner.

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