Dark mode is a must-have feature in modern web apps. It enhances user experience and can reduce eye strain. In this post, we'll walk through how to implement a Dark Mode Toggle in a React app using the Context API to manage state globally.
We'll create a simple app where users can toggle between dark and light modes, with their preference stored in localStorage so it persists even after they leave or reload the page.
Step 1: Set up the Context
The first step is to create a ThemeContext that will provide the dark mode state and the toggle function to any component in the app.
// src/context/ThemeContext.js
import React, { createContext, useState, useEffect } from 'react';
export const ThemeContext = createContext();
export const ThemeProvider = ({ children }) => {
const [darkMode, setDarkMode] = useState(() => {
const savedMode = localStorage.getItem('dark-mode');
return savedMode === 'true' || false;
});
useEffect(() => {
localStorage.setItem('dark-mode', darkMode);
document.body.className = darkMode ? 'dark-mode' : '';
}, [darkMode]);
const toggleDarkMode = () => {
setDarkMode((prevMode) => !prevMode);
};
return (
<ThemeContext.Provider value={{ darkMode, toggleDarkMode }}>
{children}
</ThemeContext.Provider>
);
};
Here, we're using useState to initialize the theme based on localStorage. useEffect ensures that whenever the theme changes, it updates localStorageand applies the appropriate class to the body element.
Step 2: Create the Toggle Component
Here, we use useContext to consume the darkModevalue and toggleDarkMode function from the ThemeContext.
// src/components/ThemeToggle.js
import React, { useContext } from 'react';
import { ThemeContext } from '../context/ThemeContext';
const ThemeToggle = () => {
const { darkMode, toggleDarkMode } = useContext(ThemeContext);
return (
<button onClick={toggleDarkMode}>
{darkMode ? 'Switch to Light Mode' : 'Switch to Dark Mode'}
</button>
);
};
export default ThemeToggle;
Step 3: Apply Dark Mode Styles
To see the dark mode in action, you'll need to add some CSS styles. For simplicity, we'll apply a dark theme to the bodyelement.
/* src/styles.css */
body {
margin: 0;
font-family: sans-serif;
transition: background-color 0.3s ease;
}
body.dark-mode {
background-color: #121212;
color: white;
}
Step 4: Set up the App Component
Here, we wrap the entire app inside the ThemeProvider, which allows the dark mode state and toggle function to be available globally.
// src/App.js
import React from 'react';
import { ThemeProvider } from './context/ThemeContext';
import ThemeToggle from './components/ThemeToggle';
import './styles.css';
function App() {
return (
<ThemeProvider>
<div className="App">
<h1>Dark Mode Toggle with Context API</h1>
<ThemeToggle />
</div>
</ThemeProvider>
);
}
export default App;
By using React's Context API, we made the dark mode state easily accessible across the app without prop-drilling. Adding localStorage ensures the theme preference persists, even after a page reload or revisit.
Feel free to tweak this basic implementation by adding more components and styles as per your needs.
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