REACT COMPONENTS
Tags: beginners, react, webdev, programming
Published: 2024-01-17 01:50:00

## INTRODUCTION
In React, components are like building blocks of a webpage. They are small, reusable pieces of code that handle specific tasks. Each component is responsible for a particular part of the user interface, making it easier to manage and organize the overall structure of a web application. For example, you create a "Button" component that represents the code for a button. This component defines how the button should look and what should happen when someone clicks on it. Once you've made this "Button" component, you can use it in different parts of your app – maybe for submitting forms, navigating to another page, or any other action that involves a button. 


**TYPES OF COMPONENTS**

Now, when it comes to creating components, React gives you two 
primary types: functional components and class components.

**Class Components**
Class components in React are a bit like the older, more traditional way of creating components. They follow the syntax of JavaScript classes, which might look familiar if you've worked with object-oriented programming before. They have a more extensive feature set, including the ability to manage state and use lifecycle methods. 
Here is how you would create a simple class component:

```
// src/components/ClassComponent.js

import React, { Component } from 'react';

class Button extends Component {
  render() {
    return (
      <div>
       <button>Click me</button>
      </div>
    );
  }
}

export default Button;

```

In class components, the `render` method is where you define what the component should render (display). It's a required method in class components and is responsible for returning the JSX that represents the component's UI. This method gets called automatically whenever the component needs to re-render, either because its props or state have changed, or because its parent component has re-rendered.

**Functional Components**
Functional components are like specialized, efficient JavaScript functions in React. They receive information called "props" (instructions), process them, and determine what should be displayed on the screen. They are known for their simplicity and readability. With the introduction of React hooks, functional components gained more capabilities, allowing them to manage internal data and respond to events traditionally handled by class components.

Here is how you would create a simple functional component

```
import React from 'react';

// Functional component example
function Button() {
  return <button>Click me</button>;
}

export default Button;
```
Here, the return statement inside the function body specifies what should be rendered. So, whenever `Button` is used, it will render the `<button>Click me</button>` element. Functional components in React are essentially "renderless" functions in the sense that they directly return JSX, unlike class components where you define a separate render method to specify the JSX to render.

In both examples, we've created components called Button that returns a button element with a call to action 'click me'. Now lets look into how components are being used in other parts of your application.

**Using a Component:**

Once you've created a component, you can now import and then use it in other parts of your application. Here's an example of how you might use the Button component in another file:

```
import React from 'react';
import Button from './Button'; // Assuming Button component is in the same directory

function App() {
  return (
    <div>
      <h2>Welcome to My App</h2>
      <Button /> {/* Using the Button component */}
    </div>
  );
}

export default App;
```
In the App component, we've imported the Button component and used it inside the `<div>` section. It's important to note that when we use `<Button />`, we're actually using a custom tag that represents the Button component we've created. This custom tag looks just like any other HTML tag, but instead of being a built-in element like `<div>` or `<p>`, it's a component that we've defined ourselves. 

Now Imagine if you had to create a button from scratch every time you needed one in your app – it would quickly become tedious and clutter up your code. Instead, by creating a reusable Button component, you can simplify your code and make it more readable.

Think of it like this: imagine you have a Card component that contains lots of information – maybe an image, a title, and some text. Instead of writing out all that code every time you need a card, you can create a Card component once and then reuse it wherever you need it in your app.


Whether it's a functional or class component, they both share a similar structure:

- They import React from the 'react' package.

- They define a component using either a function or a class.

- They return JSX (JavaScript XML) that describes what should be rendered on the screen.

- Finally, they export the component so that it can be used in other parts of the application.

**Key concepts of components**

**State:**
State serves as the internal data storage for a component, allowing it to manage and update its information over time. Changes to state trigger re-renders, ensuring that the UI stays in sync with the component's data. State can be managed using the `useState` hook in functional components or the `this.state` mechanism in class components.

**Props**
Props on the other hand, act as inputs to a component, providing a way for the parent component to pass information down to its children. Think of it like this, what if in the button component you wanted to use a different text other than the `Click me` each time the component is used. That is where props comes in, it allows us to create dynamic and reusable components that adapt to different contexts within our application.

**lifecycle methods**  
lifecycle methods that offer developers opportunities to hook into different stages of a component's lifecycle. From initialization to unmounting, these methods, such as `componentDidMount` and `componentWillUnmount`, allow for actions like fetching data, subscribing to events, or cleaning up resources. They empower developers to interact with the React ecosystem effectively and manage component behavior with precision.

All of these **state**, **props**, and **lifecycle methods** are fundamental concepts that drive the behavior of React components. While we've introduced them briefly here, we'll delve deeper into each topic in our upcoming articles.

*****************

**WHY USE COMPONENTS**

A. **Modularity and Reusability:**

- **Breakdown of UI:**
Components allow breaking down the user interface into smaller, manageable pieces. Each component represents a specific part of the UI, making it easier to understand and maintain.

- **Reusability:**
Once created, components can be reused throughout the application or even in different projects. This reusability reduces redundancy in code and promotes a more efficient development process.

B. **Maintenance and Scalability:**

- **Easy to Maintain:**
Components promote code organization, making it easier to locate and fix issues. Maintenance becomes more straightforward as changes can be isolated to specific components without affecting the entire application.

- **Scalability:**
 As your application grows, the modular nature of components allows you to scale the development process. New features or sections of the application can be added by creating and integrating new components.

C. **Readability and Understandability**

- **Code Readability:**
 Components contribute to clean and readable code. By encapsulating specific functionality, components make the codebase more comprehensible.

- **Ease of Onboarding:**
 For new developers joining a project, understanding and contributing to the codebase is more straightforward when components are well-structured and organized.

**CONCLUSION**

In this article, we've laid the groundwork for understanding React components, the fundamental building blocks of React applications. We've covered the basics, from defining what components are to differentiating between functional and class components. Understanding these concepts is crucial as they form the foundation of React development.

While we've touched on key concepts like props, state, lifecycle methods, and event handling, it's important to note that we've only scratched the surface. In upcoming articles, we'll delve deeper into these topics, exploring how props and state drive component behavior and how lifecycle methods allow components to interact with the React ecosystem.

So, stay tuned for more in-depth discussions on these topics. By building upon the knowledge gained here and exploring these concepts further, you'll be well-equipped to create dynamic and interactive user interfaces with React. Happy coding, and see you in the next article! ❤️