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Bridget Amana
Bridget Amana

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How to Easily Add Dark Mode to Your Website

Hey! So, if you’re like me and love the whole dark mode vibe, you might have thought about adding it to your website. It’s pretty easy to set up with just a bit of CSS and JavaScript. Here’s how I did it.

Step 1: Setting Up the HTML

First off, you need a button or a switch that users can click to toggle between light and dark modes. I went with a simple button for this example(you can use an icon if you want):

<button id="dark-mode-toggle">Toggle Dark Mode</button>
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This button is going to be the trigger for switching modes.

Step 2: Adding the CSS for Light and Dark Modes

Next, you need to define what your light mode and dark mode will look like. In your CSS, you’ll set up the default styles (which will be your light mode) and then add a dark mode class that overrides these styles.

body {
    background-color: white;
    color: black;
    transition: background-color 0.3s, color 0.3s;
}

.dark-mode {
    background-color: #121212;
    color: #ffffff;
}
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Here’s what’s happening:

  • Light Mode (Default): The body has a white background and black text. I added a transition to make the change smooth when switching between modes.
  • Dark Mode: The .dark-mode class changes the background to a dark grey and the text to white.

Step 3: Switching Between Modes with JavaScript

Now comes the part where we make the button actually do something. This bit of JavaScript will toggle the .dark-mode class on the body whenever the button is clicked.

const toggleButton = document.getElementById('dark-mode-toggle');
const body = document.body;

toggleButton.addEventListener('click', () => {
    body.classList.toggle('dark-mode');

    // Save the user's preference in local storage
    if (body.classList.contains('dark-mode')) {
        localStorage.setItem('theme', 'dark');
    } else {
        localStorage.setItem('theme', 'light');
    }
});
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Here’s a breakdown:

  • Toggle the Class: When the button is clicked, we toggle the .dark-mode class on the body. This changes the styles between light and dark modes.
  • Saving Preference: I added a little extra by saving the user’s preference in localStorage. This means if they choose dark mode, it’ll stay that way even if they leave and come back to the site.

Step 4: Loading the User’s Preference on Page Load

To make sure the site loads in the user’s preferred mode, you need to check localStorage when the page loads and set the mode accordingly.

window.addEventListener('load', () => {
    const savedTheme = localStorage.getItem('theme');
    if (savedTheme === 'dark') {
        body.classList.add('dark-mode');
    }
});
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If you’re using React, the process is pretty similar, but you’ll handle things within your components. Here’s how to do it:

  1. Set Up State and CSS Class for Dark Mode:

Use React’s useState to manage the dark mode state, and apply the appropriate class to your root element:

   import React, { useState } from 'react';

   function App() {
       const [darkMode, setDarkMode] = useState(false);

       const toggleDarkMode = () => {
           setDarkMode(!darkMode);
       };

       return (
           <div className={darkMode ? 'dark-mode' : ''}>
               <button onClick={toggleDarkMode}>
                   {darkMode ? 'Switch to Light Mode' : 'Switch to Dark Mode'}
               </button>
           </div>
       );
   }

   export default App;
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In this example:

  • The darkMode state determines if the dark mode is active.
  • The toggleDarkMode function toggles the dark mode on and off.
  1. CSS for Dark Mode:

Add the .dark-mode class to your CSS, just like before:

   body {
       background-color: white;
       color: black;
       transition: background-color 0.3s, color 0.3s;
   }

   .dark-mode {
       background-color: #121212;
       color: #ffffff;
   }
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  1. Local Storage:

If you want the theme preference to persist, you can add this small tweak:

   import React, { useState, useEffect } from 'react';

   function App() {
       const [darkMode, setDarkMode] = useState(() => {
           const savedTheme = localStorage.getItem('theme');
           return savedTheme === 'dark';
       });

       useEffect(() => {
           localStorage.setItem('theme', darkMode ? 'dark' : 'light');
       }, [darkMode]);

       return (
           <div className={darkMode ? 'dark-mode' : ''}>
               <button onClick={() => setDarkMode(!darkMode)}>
                   {darkMode ? 'Switch to Light Mode' : 'Switch to Dark Mode'}
               </button>
           </div>
       );
   }

   export default App;
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Here’s what’s happening:

  • Initial State: The initial state of darkMode is set based on the value stored in localStorage.
  • Effect Hook: The useEffect hook saves the current theme preference whenever darkMode changes.

And that’s it! This is a simpler way to add dark mode to your React app without overcomplicating things.

Top comments (9)

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jonathanbout profile image
Jonathan Bout

Please, instead of defaulting to light mode, use the prefers-color-scheme media query so I'm not blinded anyways on your dark mode-capable site.

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bridget_amana profile image
Bridget Amana

Totally agree😅

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za_sha_acaf876927be8ff3fd profile image
Za Sha

Good reference for both beginners and intermediate developers

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bridget_amana profile image
Bridget Amana

Glad you found it helpful

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abhinowww profile image
Abhinav Anand

nice ! quick and short

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bridget_amana profile image
Bridget Amana

Exactly what I was going for, no one likes a long and boring tutorial

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juji profile image
Tri Rahmat Gunadi • Edited

to prevent flickering, you might want to setup css as the first thing the browser do. That is, to put a script tag as the first item in the body tag.

Checkout how next-themes do it:
github.com/pacocoursey/next-themes...

Setting a script tag as the first tag in the body also allows you to get values in localStorage

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nachodev profile image
Fortune Iheanacho

Nice guide 👏

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thatsawwal profile image
Awwal Adeyemo

Thank you Bridget