ReactJS: Functional vs. Class components

 w, tags: functional class -

When it comes to a React component, there are two methods to write it. One is class-based, and the other is function-based. This leads to the question: What sets these two components apart?

Here’s the short of it: Functional components are JavaScript functions that receive props as input and return a React element, whereas Class components are JavaScript classes that extend the React component class.

Functional components are more straightforward than class components by not involving lifecycle methods or constructors.

On the other hand, class components offer a more extensive range of features and capabilities, including state management, lifecycle methods, class instance methods, and more.

Why programmers use functional components

Besides being easier to understand, functional components can be tested more easily using standard JavaScript testing tools like Jest and reused in various application sections. They also remove the overhead of creating a new instance for every render.

More importantly, functional components can take advantage of React hooks, allowing the use of state and other React features.

React Hooks has enabled functional components to handle state using the useState Hook, effectively manage lifecycle events using the useEffect Hook, access DOM elements or component instances using the useRef Hook, and much more.

Functional components in React also inherently exhibit low coupling due to their self-contained structure. This means any changes that are made within the component have minimal impact on the rest of the codebase. This factor supports modularity and maintainability, allowing for modifications without causing widespread effects as it contributes to cleaner and more manageable code in React applications.

One more special advantage of functional components is that they rely on props, resulting in a single output. This simplifies the debugging process for programmers, as there is no need for constant monitoring or logging of the component state to understand its behavior.

Why programmers use class components

Class components are suitable for complex syntax and state management, whether for Redux, Relay, or internal React state or if it requires handling user events.

When it comes to handling side effects, it’s important to note they are not allowed within the render function, and lifecycle hooks provide the right place to handle them. Therefore, if a component needs data that cannot be passed as a prop, a class component is a suitable choice due to its ability to handle such situations within lifecycle hooks.

Additionally, while React hooks are very beneficial for functional components, there is one special class component called Error Boundaries that cannot be replicated in the same way using a function component.

Error boundaries in React are vital for handling errors within React applications. They are React components that catch JavaScript errors in their child component tree. When an error occurs, they log it and display a fallback UI instead of the crashed component tree.

Before error boundaries come into play, errors inside components would lead to broken UIs and negatively affect the user experience. Now, these errors can be effectively contained and handled.

Programmers can place error boundaries around the entire app or individual components for more control. They can capture errors during rendering, lifecycle methods, and constructors of the components located below them in the component tree.

Class components in React support inheritance design patterns, while functional components facilitate composition. The choice of which approach is better depends on the project’s specific requirements and the programmer’s preferences.