React is a robust JavaScript user interface toolkit that has gained popularity due to its effectiveness and adaptability. React's component-based architecture is one of its fundamental features. A React application's components are its building blocks, and creating dynamic and reusable user interface elements requires knowing how to invoke a component from within a function. In this article, we will delve into how to call a component in a function in React, providing a comprehensive guide for beginners and advanced users.
Table Content
1. What are the React Components?
2. Calling a Component in a Function
3. Using Hooks to Call a Component
4. Calling a Component Conditionally
5. Calling a Component with Props Dynamically
6. Advanced Techniques for Calling Components
7. Conclusion:
1. What are the React Components?
Functional and class components are the two basic categories into which React components can be divided. Although both are used to generate user interfaces, functional components are the standard currently particularly with the release of React 16.8's hooks. In essence, functional components are JavaScript functions that produce JSX, the syntax extension used to describe the user interface.
Functional Components
A simple JavaScript function that takes an argument called props and returns JSX is called a functional component. This is a simple illustration of a functional component:
In this example, I have created the User name function component that I will call in the App.js file.
User.js
function User(){
  return(
    <div>
    <h1>User function component called successfully </h1>
    </div>
)
}
export default User;
App.js
First, I imported the User component and called it inside the App() function.
import logo from './logo.svg';
import './App.css';
import User from './User';
function App(){
  return (
   <div className="App">
    <User />
   </div>
); Â Â
}
export default App;
Class Components
On the other hand, class components are ES6 classes that extend React.Component and has to include a render method that accepts JSX as input.
In this example, I have created the User name class component that extends the React.Component statement and I implemented the render() method that returns JSX.
User.js
import React from 'react';
class User extends React.Component{
render()
{
return(
<div>
<h1>User class component called successfully </h1>
</div>
)
}
}
export default User;App.js
I called the User class component inside the App() function after first importing it.
import logo from './logo.svg';
import './App.css';
import User from './User';
function App(){
  return (
   <div className="App">
    <User />
   </div>
); Â Â
}
export default App;
2. Calling a Component in a Function
You must be familiar with how React components work together and how to give data using props to execute a component inside of a function. We'll look at several scenarios and approaches for calling a component from within another function or component.
Calling a Functional Component from Another Functional Component
You can include a functional component as a JSX element and then call it from within another functional component. This is the easiest approach to putting components together.
In this example, I called the Greeting component within the App component.
App.js
import logo from './logo.svg';
import './App.css';
const Greeting = ({ country }) => {
 return <h1>Hello, {country}!</h1>;
};
function App(){
  return (
   <div className="App">
    <Greeting country="United States" />
   </div>
); Â Â
}
export default App;
3. Using Hooks to Call a Component
You may apply React features like state and others in functional components by using hooks. For example, you can use the useState hook to call a component based on a specified state.
Here, the Greeting component is called within the App component, and its prop name is managed using state.
App.js
import logo from './logo.svg';
import './App.css';
import React, { useState } from 'react';
const Greeting = ({ country }) => {
 return <h1>Hello, {country}!</h1>;
};
function App(){
 const [name, setCountry] = useState('United States');
  return (
   <div className="App">
    <Greeting country={name} />
    <button onClick={() => setCountry('United Kingdom')}>Click</button>
   </div>
); Â Â
}
export default App;
4. Calling a Component Conditionally
There are situations where you would want to render a component conditionally using logic. JavaScript conditional statements placed inside the return statement of our component might be used to do this.
In this example, the Greeting component is only rendered if showGreeting is true.
App.js
import logo from './logo.svg';
import './App.css';
import React, { useState } from 'react';
const Greeting = ({ name }) => {
 return <h1>Hello, {name}!</h1>;
};
function App(){
 const [name, setName] = useState('John');
 const [showGreeting, setShowGreeting] = useState(true);
  return (
   <div className="App">
   {showGreeting && <Greeting name={name} />}
   <button onClick={() => setShowGreeting(!showGreeting)}>Click</button>
   </div>
); Â Â
}
export default App;
5. Calling a Component with Props Dynamically
Additionally, dynamic props can be computed inside the parent component's function and passed to a component.
Here, the getName function dynamically computes the name prop for the Greeting component.
App.js
import logo from './logo.svg';
import './App.css';
const Greeting = ({ name }) => {
 return <h1>Hello, {name}!</h1>;
};
function App(){
 const getName = () => 'United States';
Â
  return (
   <div className="App">
   <Greeting name={getName()} />
  Â
   </div>
); Â Â
}
export default App;
6. Advanced Techniques for Calling Components
Higher-Order Components
A function that accepts a component and produces a new one is known as a higher-order component. Component logic can be reused by using HOCs as a pattern.
App.js
import logo from './logo.svg';
import './App.css';
const withGreeting = (Component) => {
 return (props) => {
  return (
   <div>
    <h1>Hello, {props.name}!</h1>
    <Component {...props} />
   </div>
);
};
};
const AppContent = () => {
 return <p>Welcome to the app!</p>;
};
const AppWithGreeting = withGreeting(AppContent);
function App(){
Â
  return (
   <div className="App">
    <AppWithGreeting name="John" />;
  Â
   </div>
); Â Â
}
export default App;
Render Props
Using a prop whose value is a function, the Render Props technique allows React components to share code.
App.js
import logo from './logo.svg';
import './App.css';
const Greeting = ({ render }) => {
 return <div>{render()}</div>;
};
function App(){
 const renderGreeting = () => <h1>Hello, John!</h1>;
  return (
   <div className="App">
    <Greeting render={renderGreeting} />
  Â
   </div>
); Â Â
}
export default App;
React Context
Data can be passed through the component tree using React Context instead of requiring individual prop passes at each level.
In this example, the Greeting consumes the context value provided by the App.
App.js
import logo from './logo.svg';
import './App.css';
import React, { createContext, useContext } from 'react';
const NameContext = createContext();
const Greeting = () => {
 const name = useContext(NameContext);
 return <h1>Hello, {name}!</h1>;
};
function App(){
  return (
   <div className="App">
    <NameContext.Provider value="John">
     <Greeting />
    </NameContext.Provider>
   </div>
); Â Â
}
export default App;
7. Conclusion:
React's core concept of calling a component inside a function makes it possible to create dynamic, reusable, and maintainable user interface components. You may effectively manage and arrange your React components by utilizing the several strategies covered, including the use of hooks, conditional rendering, Higher-Order Components, Render Props, and React Context.
Gaining expertise in these methods will enable you to create scalable, reliable programs that are simple to update and expand. The ability to call components efficiently can greatly improve your React programming abilities, regardless of your level of experience.
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