What are the Functional Components in ReactJS?

 

You've probably heard about React components if you're a web developer using React. It serves as the foundation of any React application. There is always at least one base component in a react application.

Class components and functional components are the two categories into which React components may be separated. Everything you need to know about the functional components of reacting will be covered in this post. We'll start by defining react components. What exactly are functional elements? How can states be induced in operational components? Methods for the react lifecycle in functional components? A few of the frequently asked questions will also be addressed (FAQs).

Consider the ReactJS tutorial if you're new to React programming and want to learn more about the language's foundations.

How Do React Components Work?

React components are the fundamental building pieces of every react application, as was previously described. It functions on its own and is recyclable. The react component's objective is to segment the entire display into smaller chunks. The concept and business logic for a given view is defined by each react component.

Class-based and functional base components are the two different categories of react components. Components that are based on classes are "stateful," whereas those based on functions are "stateless."

With the introduction of React 16, functional components will utilize React hooks to perform all the functions of class-based components. Development for reacting is made simpler and quicker using react hooks. Without creating classes, we can still implement React's state and lifecycle methods.

Introducing React Functional Components

Using appropriate function keywords, we can create React functional components, which are just regular JavaScript functions. Most programmers use the Arrow function to generate useful components. The main objective of the functional component is to render the view and the data to the browser.

In other words, functional components receive data. Technically speaking, they take props as a function parameter and return the data in a format that is compliant with JSX.

Passing the props to the functional components is expected in real-world applications. Every react application needs props to function. It provides information from one component to another, enabling us to create applications that are both resilient and dynamic.

It's important to keep in mind that since props are read-only, React components do not need to update their values and the same props always return the same result. Functional components are pure components because they adhere to this pattern and are referred to as such.

React Function Component Arrow

Over components with particular function keywords, arrow functions are the method of choice for most developers when developing functional components. It is easier to create components using the arrow function, and the code is clear and easy to understand. Additionally, it has the advantage that regular functions handle this context dynamically, whereas arrow functions handle it lexically.

Stateless Function Component for React

Focusing on the UI is the purpose of stateless functional components. State or lifecycle methods are absent from stateless functional components. It is simple to create and other developers can quickly comprehend it. We also don't need to be concerned about this keyword. Performance increased since we no longer had to worry about managing the state.

The state is a React Function Component.

It is now feasible to construct a state and keep the form inside the functional component thanks to React 16. React Hooks, a brand-new feature that lets us "hook" functionality into functional components, makes this possible.

The useState() hook, which is used to create the state and update the form, is one of the fundamental hooks offered by React. We can use array destructuring to extract the two crucial components from the collection—the state's current value and a function used to update the form—from the useState() function, which accepts an object as an input and returns an array.

Event Handler, a component of a React function

React gives us the same ability as javascript to call functions and run code when a user interacts with DOM components. These interactions are known as events in a technical sense; there are various kinds of interactions, including click, mouse, keyboard, etc.

Every component in React has its own markup and methods. The return() method of our component can simply call the code we've defined there.

React event handling differs mostly in two ways:

First, camelCase syntax is used across all react events; Second, inside the braces, respond invokes the handler method. Look at the bit of code below.

Activate Function Callback Function, part

Every function inside a component is regenerated when it is re-rendered, so the references to these functions vary between renders.

A memoized instance of the callback will be returned by useCallback(callback, dependencies), and it will only change if one of the dependencies has changed. We can reuse the same function object between renders rather than creating a new one for each new render.

Activate Function Feature: Lifecycle

You have undoubtedly used React lifecycle methods like componentDidMount, componentDidUpdate, component will unmount, etc. if you have previously utilized class-based React components. It is also feasible to employ the behavioral lifecycle methods inside the functional components with an introduction to React 16.

componentDidMount:

After the component is mounted and rendered to the DOM, a lifecycle method runs or is put into action. After the component mounting is complete, it is only called once over the component's lifespan.

Exporting and importing using the React Function Component

As I already mentioned, components serve as the foundation for react applications. First, we must export the components from the javascript code and import them into the other javascript file where we intend to use them. We can use the standard import and export statements for components because they are simply standard javascript functions.

Function Component for React: Ref

Ref is a function used by components to access the DOM. To enable access to the element from wherever within your component without requiring properties and everything, you merely need to attach a ref to it in your application.

Refs can be used to gain direct access to React elements and to interact with them via callbacks.

Refs should only be used when the state and props are unable to deliver the desired interaction.

Any DOM manipulation that needs to be done can be done via references. Focus, test selection, media playback, starting required animations, or interacting with a third-party DOM library are a few examples.

Activate Function Feature: Proptypes

React uses PropTypes as its internal type verification mechanism for components. PropTypes is a specific property that Reacts components utilize to configure type verification.

Typescript is a React function component.

A strictly typed language, typescript is a superset of javascript. Try building components in Typescript if your React application requires a strongly typed system.