React JS is an open-source front-end library designed to create fast and interactive user interfaces for web and mobile applications. It was developed by Facebook and has gained immense popularity due to its ability to enhance the look and feel of websites. While React JS appeals to beginners in the development field, many aspiring developers often make the mistake of diving directly into React JS without understanding the foundational knowledge required. This can lead to significant challenges during the learning process and even in job interviews.
It is crucial for developers to recognize that React JS builds upon certain prerequisites that form the foundation of its usage. By disregarding these prerequisites, developers may struggle to grasp the concepts and effectively utilize React JS to its full potential.
Scope
Fundamental Web Technologies:
Before diving into React JS, it's crucial to have a solid understanding of foundational web technologies like HTML, CSS, and JavaScript.
JavaScript Proficiency:
A strong grasp of JavaScript concepts and features is vital for working effectively with React JS. This includes variables, functions, loops, conditionals, and knowledge of JavaScript frameworks and libraries.
ECMAScript 6 (ES6):
Familiarity with modern JavaScript syntax, particularly ES6, is highly recommended. This includes concepts like arrow functions, classes, modules, template literals, and the spread operator, which are commonly used in React JS development.
Virtual DOM:
Understanding the Virtual DOM is essential in comprehending React JS's underlying mechanism. The Virtual DOM is a representation of the actual DOM and enables efficient updates and rendering of UI components.
Promises in JavaScript:
Familiarity with promises, which are used for asynchronous programming in JavaScript, is beneficial when working with React JS. Promises allow developers to handle asynchronous operations and manage data flow effectively.
Arrow Functions:
Understanding arrow functions, a concise syntax for defining functions in JavaScript, is important as they are commonly used in React JS for defining component methods and event handlers.
Rest and Spread Operators:
Knowledge of the rest and spread operators in JavaScript is valuable in React JS development. The spread operator (...) is often used for merging arrays or objects, while the rest operator allows capturing multiple function arguments into a single array.
React JS's Popularity:
Companies often prefer React JS over other tech stacks due to its numerous advantages. React JS offers a modular and component-based approach, facilitates code reusability, has a large and active community, provides excellent performance with the Virtual DOM, and is well-suited for building scalable and interactive user interfaces.
Introduction
React.js's release expanded front-end programmers' capabilities for creating intuitive user experiences.
React.js, developed by Facebook, garners extensive support from the community. It excels in building Single Page Applications (SPAs). React's efficiency, component-based architecture, virtual DOM, and declarative syntax drive its popularity. Its vast ecosystem and industry recognition further contribute to its widespread adoption.
In 2011, Facebook developers faced maintenance issues as their Ads app expanded in capabilities. The growing number of employees and app functionalities slowed down operations. With frequent updates, the software became increasingly difficult to manage, posing challenges for the team.
React's beloved features like Components, DOM Virtualization, Lifecycle Methods, JSX, and React Hooks contribute to its success. These collectively offer three key benefits: a strong community, high performance, and clean code. These advantages, coupled with the prerequisites for learning ReactJS, make it a popular choice among developers.
Essential Prerequisites for Learning ReactJS
Below are the key prerequisites for learning ReactJS, an essential JavaScript library for front-end development.
HTML and CSS
HTML is the fundamental language for structuring web content. It defines headers, paragraphs, links, and other components, enabling browsers to interpret and organize web pages accordingly. CSS complements HTML by providing styles and visual enhancements to create engaging and well-designed websites.
CSS is a vital tool for designing visually appealing websites, providing the means to enhance aesthetics through fonts, colors, backgrounds, and engaging transitions. It enables the creation of stunning web pages, imbuing them with elegance and captivating 3D effects, making them visually impressive and user-friendly.
Proficiency in HTML and CSS is essential for front-end developers as they form the foundation before diving into learning React.
Before diving into React.js, it is crucial to first learn HTML and CSS, including creating semantic HTML tags, writing CSS selectors, utilizing classes, implementing CSS resets, understanding the box model and border-box, and grasping flexbox for building front-end and responsive web applications.
Fundamentals of JavaScript and ES6
JavaScript ES6, also known as ECMAScript 6, brings forth a multitude of changes and enhancements. With its fantastic new features and syntax, code becomes more modern and readable. ES6 empowers developers to achieve more with less code by introducing features such as Modules, template strings, class destruction, and arrow functions.
To prepare for React, mastering ES6 is essential as hooks are replacing class-based components. Hooks heavily rely on ES6 features, making it crucial to have a solid understanding of them beforehand.
If you are not comfortable with writing arrow functions, utilizing React can be challenging since several hooks require nesting them, leading to potential confusion.
Understanding ES6 is crucial for React JS and JavaScript developers as it simplifies reading and writing React JS code, leading to an improved development experience and enhanced productivity.
Git and CLI (Command Line Interface)
Git is a highly significant and effective tool in the software development process, playing a crucial role in version control and collaboration.
Git is a distributed version control system designed for tracking source code changes during application development. It enables monitoring of progress in any filesystem and fosters collaborative development among developers.
To effectively track file versions, learn and utilize commands like push, pull, add, commit, etc. Additionally, grasp merging, branching, and handling merge conflicts to enhance your ability in version control with Git.
Package Manager (Node + Npm)
While using ReactJS, it is crucial to install multiple smaller software packages. These packages, containing JavaScript files and package.json files, are essential for Node projects and serve as modules. To simplify the process and avoid dependency issues, a reliable installer is necessary for downloading and setting up these packages.
Node Package Manager (NPM) is a vital tool for installing and managing JavaScript applications. It seamlessly integrates with Node.js, making the setup process straightforward. Once you install Node.js, NPM is automatically configured and ready to be used for package installation and management.
Download Node.js from the official website. Click here.
The recommended approach for starting a new React single-page application is by utilizing Create React App. It provides a user-friendly environment that facilitates learning and development in React.
Follow these steps to create a sample project using the commands below.
Before transitioning to React, it is crucial to have a solid understanding of NPM (Node Package Manager) registry and package installation methods. Essentially, the NPM registry serves as a central repository where developers can access the necessary software for software development.
ES6 variables - Let and Const
In the pre-ES6 era, developers used to declare variables using the "var" keyword or with no keywords. However, with the advent of ES6, there have been significant changes in variable declaration and assignment.
With the introduction of ES6, JavaScript embraced a new era by incorporating two keywords, "let" and "const," for variable declaration. These keywords vary in scope, defining the accessibility of variables within functions, blocks, or both.
var:
The functional scope level -
The "var" keyword in JavaScript has functional scope, meaning variables declared inside functions cannot be accessed outside of them.
let:
The block scope level -
The "let" keyword in JavaScript provides block scope, allowing variables to be accessed outside of the scope of their declaration.
const:
The block scope level -
The "const" keyword in JavaScript, similar to "let," operates with block scope. However, a variable declared with "const" is a constant and cannot be modified through redeclaration or reassignment.
Arrow Functions
One of the new features introduced in ES6 is the arrow function in JavaScript. It provides a simplified syntax compared to conventional functions, making function writing more concise and straightforward.
Arrow functions simplify code and enhance readability.
They eliminate the need to "bind" functions, thanks to contextual "this".
Arrow functions are widely supported by modern browsers.
Contextual "this" in arrow functions eliminates the confusion around function scope and provides a more intuitive way to access variables.
Exports and Imports
ES6 introduced the ability to create modules in JavaScript, which can encapsulate classes, functions, variables, and objects. JavaScript modules enable code organization across multiple files, resulting in improved code maintenance and manageability.
To make module members accessible in another file, JavaScript provides export and import statements. By utilizing these keywords, you can export and import specific members from a module, allowing for efficient code sharing and reuse.
Rest and Spread Operator
In JavaScript, the spread and rest operators are denoted by three dots, (...). While they share the same syntax, they serve different purposes. The rest operator collects the remaining user-supplied values into an array, while the spread operator expands an iterable into its individual elements. This distinction allows for flexible handling of data in various scenarios.
Object and Array Destructuring
Destructuring in JavaScript involves unpacking individual components from objects or arrays. It enables modification and swapping of elements once they are unpacked, providing flexibility for performing specific actions on the data. This feature enhances code readability and simplifies data manipulation tasks.
In JavaScript, array destructuring is achieved using square brackets []. It allows assigning variables to the elements of an array based on their position, simplifying the process of accessing and working with array elements.
When destructuring objects in JavaScript, we use curly braces {} with the precise names of the properties to unpack the elements. Unlike arrays, object destructuring requires using the exact property names for unpacking, limiting the flexibility of variable naming.
Template Literals
ES6's Template Literal introduces flexible string generation capabilities. Traditionally, strings were created using single or double quotes, but Template Literals, denoted by backticks, provide enhanced dynamic string functionality.
Template literals in JavaScript are string literals enclosed in backticks (`) that allow for embedded expressions, string interpolation, and multi-line strings. Previously referred to as template strings, they provide enhanced string manipulation capabilities.
Map Filter and Reduce
JavaScript provides three array functions: map, reduce, and filter. These functions iterate over an array, performing transformations or operations, and generate a new array based on the function's output.
The map() method creates a new array by applying a function to each element of the original array.
The filter() method evaluates a conditional statement for each element in an array. If the condition is true, the element is included in the output array. If false, the element is excluded from the output array.
The reduce() method reduces an array of values to a single value by applying a reducer function to each element of the array, resulting in an output value.
This in Browser
In JavaScript, the behavior of the this keyword in functions differs from other languages. It also takes into account strict and non-strict modes, affecting its functionality.
The value of the this keyword in JavaScript is typically determined by the invocation of a function (runtime binding). It cannot be set during execution via assignment, resulting in potentially different values each time. However, the bind() method allows explicit setting of a function's this value regardless of the invocation method.
Promises and Async Await
In JavaScript or Node.js, multiple methods exist for handling operations asynchronously. These operations execute concurrently and are processed as soon as their output becomes available.
In Node.js, a Promise functions similarly to a real-world promise, ensuring that an action will be taken. It manages the outcome of an asynchronous event and tracks whether the event has been completed or not.
Promises are handled using Async/Await in asynchronous methods. This coding style simplifies the usage and readability of promises, making asynchronous programming resemble synchronous code and easing the development process.
Why do Companies Prefer React js?
Companies often prefer ReactJS for several reasons:
Reusability and Component-Based Architecture:
ReactJS promotes the development of reusable components, enabling companies to efficiently build and maintain large-scale applications. This component-based architecture allows for modularity, code reusability, and easier collaboration among developers.
Virtual DOM and Efficient Rendering:
ReactJS utilizes a virtual DOM, which optimizes rendering performance by updating only the necessary components rather than the entire DOM. This results in faster and smoother user interfaces, enhancing the overall user experience.
Rich Ecosystem and Community Support:
ReactJS has a thriving ecosystem with a wide range of libraries, tools, and community support. This abundance of resources simplifies development, improves productivity, and facilitates the integration of ReactJS with other technologies.
Scalability and Performance:
ReactJS enables scalable application development. It allows for the creation of complex and feature-rich applications while maintaining performance. The efficient rendering process and optimized updates contribute to the scalability and high performance of ReactJS applications.
Strong Industry Adoption:
ReactJS has gained significant popularity and adoption across various industries. Many well-established companies, including Facebook, Instagram, Airbnb, and Netflix, have successfully implemented ReactJS in their projects, instilling confidence in its reliability and effectiveness.
React Native for Mobile Development:
ReactJS's sibling framework, React Native, allows for cross-platform mobile app development using the same React principles. This code reuse potential for web and mobile development further attracts companies looking for efficient multi-platform solutions.
Conclusion
ReactJS is an open-source front-end library focused on creating fast and interactive user interfaces for web and mobile applications.
To work with ReactJS, you need a basic understanding of HTML and CSS, JavaScript and ES6 fundamentals, familiarity with Git and CLI, and knowledge of the package manager (Node + Npm).
To work with ReactJS effectively, you should be familiar with ES6 variables, arrow functions, exports and imports, rest and spread operators, object and array destructuring, and the this keyword in JavaScript.
A template literal is a string literal that enables embedded expressions by using backtick characters.
JavaScript provides map, reduce, and filter as array functions for iterating over arrays and performing various operations.
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