Comparison Between React Elements and React Components

React is a powerful JavaScript library, and it is widely used for creating responsive web pages. React simply creates interactive UIs by rendering elements and breaking them into smaller, reusable parts. There are two main concepts in ReactJS:

1. React Elements

2. React Components

Building Blocks of ReactJS

Before diving into react elements vs react components, we first need to understand the basic building blocks of reactJS. The React application is made up of a number of small parts that work very smoothly together. This small part would contain react elements, react components, and simple building blocks. It would also contain multiple elements and multiple components.

ReactJS is one of the most popular libraries for creating and rendering a single-page web application with a smooth user experience. So developers must know and understand the difference between an element and a component. In this blog, we will learn what the key features of elements and blogs are, what the differences are between them, and how they work in ReactJS.

What is a React Element?

In a React application, a React element is the most basic unit of app component. It’s an immutable object that specifies what should appear on the screen. React elements are the fundamental components of a React app and can represent HTML elements tags like <div>, <h1>, <p>, or even custom components.

Core Features of React Elements

• Immutability: Once a React element is created, it cannot be altered. A new element must be generated to reflect changes in the UI.

• Simplicity: React elements are basic objects used by React to construct the DOM element. They do not handle any logic or state.

• Static Nature: Essentially, a React element is a plain JavaScript object describing a DOM node or another component, including attributes such as type, props, and children.

How to Create React Elements

React elements can be created either through JSX (JavaScript XML) or the React.createElement() method.

// Example with JSX:
const element = <h1>Hello, world!</h1>;

This JSX creates a React element for an <h1> tag with the text "Hello, world!".

// Example with React.createElement
Example with React.createElement():
const element = React.createElement('h1', null, 'Hello, world!');

What is a React Component?

React components are more advanced than elements. They serve as the building blocks of other components in a React application and define sections of the user interface. Unlike elements, components can handle their own state and lifecycle methods, adding flexibility and complexity.

Types of React Components:

• Functional Components: These are javascript functions that accept props and return React elements. They do not have internal state or lifecycle methods.

• Class Components: These are ES6 classes extending React.Component. They can manage state and include lifecycle methods, suitable for more intricate UI logic.

Key Attributes of React Components:

• Reusability: Components are designed to be reused throughout an application, supporting the DRY (Don’t Repeat Yourself) principle.

• State Management: Components can be either stateful, handling their own state, or stateless, depending solely on props from parent components.

• Lifecycle Methods: Class components have access to lifecycle methods like componentDidMount, componentDidUpdate, and componentWillUnmount, enabling code execution at various stages of the component’s lifecycle.
  

How to Create React Components

//Example of a Functional Component:
function Welcome(props) { 
	return <h1>Hello, {props.name}</h1>;
 }
//Same example using Class Component:
class Welcome extends React.Component {
 render() { 
	return <h1>Hello, {this.props.name}</h1>;
 	} 
}

Comparing React Elements and Components

React Elements Vs React Components

• Purpose and Function:

  Elements: They represent the static description of what should be shown on the screen. Elements are immutable and describe the structure of the UI at a specific point in time.

  Components: They define both the behavior and appearance of the UI. Components encapsulate logic, state, and other elements or components, making them the building blocks of complex applications. They render elements based on the current state and props in javascript function.

• Creation and Usage:

  Elements: Created using JSX or React.createElement(). They are simple, lightweight objects that describe what you want to see on the screen. Elements do not handle state or logic, as they are purely declarative.

  Components: Can be functional or class-based. They are more complex structures capable of managing state, handling events, and defining life-cycle behavior. Components can be nested and reused throughout the application, providing modularity.

• Reusability:

  Elements: Usually represent a single instance of a UI node and are not typically reused. Since they are static and specific to a point in time, elements are generally recreated whenever the UI needs to be updated.

  Components: Can be reused multiple times with different props to build complex user interfaces. Components enable developers to create reusable, maintainable code by breaking down the UI into smaller, manageable parts.

• State Management:

  Elements: Stateless and immutable. Once an element is created, it cannot change. If the UI needs to change, a new element must be created.

  Components: Can manage state or remain stateless, depending on their design. Stateful components allow for dynamic UI updates, responding to user interactions or other changes in data. Stateless components are simpler and often used for presentational purposes.

• Lifecycle Methods:

  Elements: Do not include lifecycle methods as they are static. They are just plain objects representing the UI and do not have the ability to manage or react to changes over time.

  Components: Class components can utilize lifecycle methods to perform actions at different stages, such as mounting, updating, or unmounting. This allows developers to handle side effects, optimize performance, or clean up resources when necessary.

Practical Applications

Using React Elements:

const element = (
  <div>
    <h1>Hello, Universe!</h1>
    <p>Welcome to React world.</p>
  </div>
);
ReactDOM.render(element, document.getElementById('root'));

This example shows how to directly specify what should be rendered to the DOM with React elements, without involving state management function components, or reusable logic.

Using React Components:

function Greeting(props) {
	return ( 
   		<div>
   		 <h1>Hello, {props.name}!</h1>
    		 <p>Welcome to React world.</p> 
  		 </div> 
	);
 }
 ReactDOM.render(<Greeting name="Universe" />, document.getElementById('root'));

In this case, the Greeting component is dynamic and reusable. It can accept different props and display a customized greeting each time it’s used.

Components and Elements

It’s crucial to understand that components are ultimately built from elements. When JSX is used in a component, React transforms this JSX into what React calls as elements. Thus, components are abstractions that organize and manage elements.

Summary

Distinguishing between React elements and components is vital for effective React development. While elements provide a static description of the UI, components bring it to life with state management and behavior. Mastering both allows React developers to build robust, maintainable, and scalable React applications.