Скачать или смотреть React Hello World App for Beginners

Want to learn React? The best place to begin is with a Hello World React app.

However, this React tutorial is targeted at developers who want to quickly gain competency with React, so we go beyond the simple printing out of 'Hello World' in React and move into other important aspects of JavaScript programming with ReactJS.

In this ReactJS course we cover variables, methods, actions and even state management.

If you want to get up to speed quickly with ReactJS, this Hello World tutorial is the perfect place to start.

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To write a "Hello, World" application in React, there are a few key prerequisites: understanding JavaScript, having Node.js installed (which provides access to npm or Yarn for managing packages), and basic familiarity with HTML and CSS. React is a JavaScript library used to build user interfaces, specifically single-page applications (SPAs), by breaking down the interface into reusable components.

Prerequisites
Before you start building your first React application, you'll need:

Node.js: React relies on Node.js to set up a development environment and manage dependencies.
Package Manager: npm or Yarn is used to install React and related packages.
Text Editor: Any code editor, such as Visual Studio Code, will do.
React CLI: Tools like Create React App (CRA) are often used to bootstrap a new project quickly.
Core Concepts
When building a React application, understanding how to declare variables, manage state, and define methods is essential. Declaring variables in React follows standard JavaScript conventions, but in the context of React components, these variables usually represent different pieces of UI data.

Using State
React uses a feature called state to manage dynamic data that may change over time. The state allows you to store and update variables that determine how your components behave and render. For example, a "Hello, World" React application might store user input in the state and update it when the user clicks a button. Managing state efficiently makes your application interactive and user-friendly.

Methods and Actions
Adding methods to your React component is critical for defining the behavior of your application. These methods handle the logic of how the UI responds to different actions, such as a button click. Methods can be used to update the state, make API requests, or manipulate DOM elements. Actions can be triggered from buttons, links, or other interactive elements by associating them with event handlers like onClick or onChange. This interactivity is at the core of what makes React powerful.

Benefits of React
React offers several advantages over other popular frameworks:

Component-based architecture: React organizes your application into small, reusable components. Each component has its own logic and structure, making the code more maintainable and easier to debug. This modularity contrasts with older, monolithic approaches found in traditional frameworks.

Virtual DOM: One of React’s most significant features is its virtual DOM. Instead of directly interacting with the real DOM, React updates a virtual representation, only applying the minimal necessary changes. This results in better performance, especially for larger applications.

Unidirectional data flow: React’s one-way data flow, also known as one-way binding, ensures that data moves in a clear, predictable direction. This makes debugging and understanding the application’s state flow easier compared to frameworks with two-way data binding, such as Angular.

React vs. Other Frameworks
React vs Angular: Angular is a full-fledged framework with two-way data binding, a steeper learning curve, and built-in features like routing and dependency injection. React, on the other hand, is more lightweight and flexible, allowing developers to pick and choose additional libraries.

React vs Vue: Vue is similar to React in its component-based architecture, but it offers a bit more out of the box, like built-in directives. However, React’s large ecosystem and community make it a safer bet for large projects.

React's approach to building UI by breaking down the interface into reusable components and handling state efficiently makes it a dominant choice in web development. Its simplicity, combined with powerful performance features like the virtual DOM, makes React a strong contender against frameworks like Angular and Vue.