July 11, 2023
Before React components, development was like a nightmare for today’s developers, thousands of lines of code when developing a single-page application put together a single file of conventional DOM structure. The worst was the thought of modifying or updating that file.
Today’s ReactJS development companies can have a sigh of relief with the introduction of components especially Hook in React version 16.8.
React Components are often referred to as wall’s brick-logical, independent, and reusable code pieces of application which simplify User Interface (UI) creation. These components can either be React Class or Function which accepts props(properties are a type of object) and returns a React element.
This is where the debate starts amongst the React.js community of React functional components vs class components.
Before we jump into knowing about React classes vs functions, let us first understand them individually.
“Hooks are a new addition in React 16.8. They let you use state and other React features without writing a class.” – reactjs.org
Known for a substantially lesser amount of code, these components can accept and use props(properties). React lifecycle methods and render method(componentWillMount(), componentDidMount(), or render()) are not used in the React functional components.
Class component in React are slightly different from React functional components, let us find out more about the class components.
When it comes to features ReactJS Class has more to offer as it includes constructors, life cycle methods, render functions, and state/data management making these React components more powerful and versatile. As the Class component in React is “stateful” the ease the management/handling of state/user events.
Now, let us see get insights to React functional components vs class components on some of the crucial aspects.
The state in React is used by ReactJs programmers to manage component actions. Handling the state was only possible with React Class component until the introduction of Hooks in React 16.8 which enables the React experts to create stateful functional components in React.
As seen in the example below of the basic counter, to handle the state in the function component useState() Hook is used.
In the case of the Class component, the use of the setState() function is done for executing a similar logic. To begin with, a constructor is to be defined to create a state object with a state key and initial value (() here).
To update the value of count this.state.count is used in the setState() function of the render() method. Like the functional component, the class component would display the number of times a button was clicked but the line of code is more than the former one.
The winner of React functional components vs class components or preferable React Component in case of handling state is React functional components.
The React Components have a lifecycle during which they go through phases like Initialization, Mounting, Updating, and Unmounting. There are predefined methods that the React developers can use to invoke each of these phases. These methods enable the ReactJS geeks to manage the side effects.
As these lifecycle methods can only be written in class, there were no lifecycle methods in functional components until the introduction of Hooks.
If you’re familiar with React class lifecycle methods, you can think of useEffect Hook as componentDidMount, componentDidUpdate, and componentWillUnmount combined. – React
So, unlike different methods for each phase of the lifecycle in React class component, for the functional component, you can use one hook useEffect to manage the side effects like fetching data or managing subscriptions.
Here is the example of the mount and unmount lifecycle phase with the use of useEffect Hook with an empty dependency array () and a cleanup function returned respectively.
Similarly, for componentDidUpdate, you must use useEffect Hook with a dependency array containing state/prop values to check for any update. In the functional component, for shouldComponentUpdate there is React.memo or useMemo Hook. To update the state based on props (getDerivedStateFromProps) in the function component, you can use useMemo or useEffect Hook.
To invoke the same phases of the lifecycle methods – mount and unmount in React class component, ReactJS developers have to use two separate methods componentDidMount() and componentWillUnmount().
In the case of lifecycle methods, for React functional vs class components, the Functional class in React leads in terms of its Simplicity.
Abbreviation of ‘Properties’, props are read-only and immutable objects which store a value (objects, arrays, and functions). These arbitrary inputs are passed to the component via HTML attributes just as an argument in a function. These objects are used by the React component to communicate/transfer data with each other.
Let us find out how these props are passed in in each of these React components.
In a Functional component, a prop is passed as an argument to the function.
While in React class component, the props here are props objects which can be accessed via this keyword since class components extend React.Component.
As it is easier to pass props in functional components with Hooks, for React class vs functional component, functional beats the class component.
One of the major differences which enable Functional components in React to gain popularity over the class is to the extent that the React coders started assuming that class components are outdated and almost on the verge of removal. Even the official documentation of React has mentioned that” There are no plans to remove classes from React.”
Here are some of the most essential React hooks:
Hooks can’t be used inside a class.
|Extend from React.Component
|Don’t extend from React.Component
|Do not have any Lifecycle Methods, uses React hooks instead introduced in React in version 16.8
|Has different life cycle methods for invoking different phases of component lifecycle
|Fewer lines of code
|Lengthier code lines
|Don’t maintain state information
|Maintains state information
|Do not use any render method
|Use render() method
|Functional components eliminate the use of the “this” keyword
|Class components use the “this” keyword
|Don’t support a constructor
|Require a constructor as the state needs to be stored
|Support React 16.8 Hooks
|Don’t Support React 16.8 Hooks
|Functional components are more efficient
|Class components are a little inefficient
|Uses React Hooks to manage state
|Has built-in state management using this.state
|Props are passed as a parameter to the function
|Props are accessed through this.props
|Help developers to use best practices
|Easier to cause performance issues
|React requires less work to render these components.
|React requires more work to render these components.
|Easier to read and test
|Harder to read and test
|Uses less memory
|Uses more memory
|Supports inheritance design patterns
With the introduction of React Hooks the popularity of React functional components has grown tremendously so much so that the Class components have turned out to be obsolete. However, though the functional components offer simplicity and faster development the Class component in React increases the code reusability and features when developing high-quality front-ends. The unique aspect is the Error Boundaries exclusive to the class component.
Depending on the requirements the ReactJs developers can choose either of these components.
Here are some recommendations that would help you to make a more informed decision about choosing between the React class component vs functional component.
The developer can use the Class Component in the following scenario:
The developer can use the Functional Component in the following scenario:
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