How to implement Conditional Rendering in React?

This article explores JavaScript's conditional rendering in React JS, including various methods, syntax, and applications, leveraging React's virtual DOM, reusable components, props, and rapid rendering capabilities in single-page UI applications.

We will use the following approaches to implement conditional rendering in React

if-else statements:

if(condition){
    expression1 
}
else{
    expression2
}

if-elseif statements:

if (condition) {
    expression1
}
elseif(condition){
    expression2
}
else {
    expression3
}

'&&' operator:

condition && expression

A short-circuit logical AND is represented by the && operator. If this condition is satisfied, the following && expression shall be considered; if not, it shall be disregarded entirely. For simple conditional rendering, this approach is brief and widely used.

'&&' operator with the alternative operator '||':

condition && expression1 || expression2

If the condition is incorrect, a && operator and || can be combined to produce an alternate expression if there is a need for fallback expressions. This allows for different rendering scenarios to be handled more flexibly.

using ternary ( ?: ) operator:

condition ? expression1 : expression2

A more explicit way of expressing conditional rendering is provided by the ternary operator. In determining whether the condition is true or false, it will return a single expression.

Steps to Create the React App:

Step 1: Create a React project:

npx create-react-app conditional-rendering

Step 2: Navigate to the project:

cd  conditional-rendering

Project Structure:

The updated dependencies in package.json file will look like:

"dependencies": {
    "@testing-library/jest-dom": "^5.16.4",
    "@testing-library/react": "^13.2.0",
    "@testing-library/user-event": "^13.5.0",
    "bootstrap": "^5.1.3",
    "react": "^18.1.0",
    "react-dom": "^18.1.0",
    "react-icons-kit": "^2.0.0",
    "react-redux": "^8.0.2",
    "react-scripts": "^5.0.1",
    "redux": "^4.2.0",
    "web-vitals": "^2.1.4"
}

Example: This example showcases a dynamic toggle switch controlled by the Dynamic App component, with UI updates based on state, and dynamic notifications indicating its status. Visual styles are managed through CSS classes, enabling modular reuse, and users can toggle the switch for immediate updates.

/* App.css */
.App {
    font-family: sans-serif;
    text-align: center;
}

body {
    margin: 0;
    padding: 0;
}

.toggle-slider {
    height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-direction: column;
}

.on {
    background-color: aqua;
}

.off {
    background-color: aliceblue;
}

button {
    padding: 10px 15px;
    border: none;
    background-color: grey;
}

import React, { useState } from "react";
import "./App.css";
const DynamicApp = () => {
    const [isToggled, setToggled] = useState(false);

    const handleToggle =
        () => {
            setToggled(
                (prevState) => !prevState);
        };

    return (
        <div className={
            `toggle-slider 
            ${isToggled ? "on" : "off"}`
        }>
            <h1>Switch Application</h1>
            <ToggleSwitch isToggled={isToggled}
                onToggle={handleToggle} />
            {isToggled ? (
                <p>The color switch is ON!</p>
            ) : (
                <p>The color switch is OFF!</p>
            )}
        </div>
    );
};

const ToggleSwitch =
    (
        {
            isToggled,
            onToggle
        }) => {
        return (
            <div
                className={
                    `toggle-switch
                    ${isToggled ? "on" : "off"}
                    `}
                onClick={onToggle}>
                <button>
                    {isToggled ? "Switch on" : "Switch off"}
                </button>
            </div>
        );
    };

export default DynamicApp;

Steps to run the app:

npm start

Output:

Example 2: This example features a basic React component showcasing hide-and-display functionality toggled by a button click. Utilizing the useState hook, it manages visibility state for dynamic UI updates.

/* Write CSS Here */
/* App.css */
.App {
    font-family: sans-serif;
    text-align: center;
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 90vh;
}

button {
    color: white;
    background-color: black;
    padding: 10px 20px;
}

import { useState } from "react";

export default function App() {
    const [showText, setShowText] = useState(true);

    const textVisibility = () => {
        setShowText(!showText);
    };

    return (
        <div className="App">
            <center>
                {!showText && (
                    <p>
                        GeeksforGeeks is a leading platform that provides
                        computer science resources and coding challenges for
                        programmers and technology enthusiasts, along with
                        interview and exam preparations for upcoming aspirants.
                        With a strong emphasis on enhancing coding skills and
                        knowledge, it has become a trusted destination for over
                        12 million plus registered users worldwide. The platform
                        offers a vast collection of tutorials, practice
                        problems, interview tutorials, articles, and courses,
                        covering various domains of computer science.
                    </p>
                )}
                <button onClick={textVisibility}>
                    {showText ? "Show some text" : "Hide it"}
                </button>
            </center>
        </div>
    );
}

Step to run the app:

npm start

Output: