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Add dark mode to your website with just a few lines of code

AlbertoM on February 17, 2020

This article was originally posted on my blog. Head over to inspiredwebdev.com for more articles and tutorials. Check out my JavaScript course on ...

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Taufik Nurrohman • Feb 17 '20

Another idea: use single theme file and just toggle a global class name…

button.addEventListener('click', () => {
    document.body.classList.toggle('dark');
    localStorage.setItem('theme', document.body.classList.contains('dark') ? 'dark' : 'light');
});

if (localStorage.getItem('theme') === 'dark') {
    document.body.classList.add('dark');
}

/* Light mode */
body {
  background: #fff;
  color: #000;
}

/* Dark mode */
body.dark {
  background: #000;
  color: #fff;
}

Arsen Ibragimov • Feb 17 '20

Good one! Thanks!

AlbertoM • Feb 17 '20

Yes you are right, I might add it to the article for completion.

Maxime Moreau • Feb 18 '20

And even better, define some css variables to change everything in just a few lines of css (variables declaration).

Anjali Chauhan • Feb 18 '21

i have more than 1 page whom i want to add dark theme. how to do that?

Anjali Chauhan • Feb 18 '21

i have more than 1 page whom i want to add dark theme. how to do that?

Thomas Bnt • Feb 17 '20 • Edited

Nice post !
But an error on example :

document.getElementByID

edit to

document.getElementById

And

<button id="theme-toggle">Switch to dark mode<button>

<button id="theme-toggle">Switch to dark mode</button>

AlbertoM • Feb 18 '20

Thanks, I've updated the post

Patryk • Feb 17 '20

According to CanIUse.com [prefers-color-scheme] support is at around 78%, leaving out Internet Explorer and Edge (not Edge Chromium).

Correct me if I'm wrong, but I don't believe browser support is enough for this feature to work properly - you also need a way to set your theme preferences in your OS. I think this is only available on Android Q (Android 10), and I am yet to find a way to set this as a preference in KDE. (No clue about OSX, Windows, and iOS, as I don't use them and had no need to research it so far).

I think it's a bit too early to adopt this, as most users will have older phones.

Pavitra Golchha • Feb 17 '20

You can always fallback to light theme in case this feature is not supported.

Patryk • Feb 17 '20

Of course. Better yet, do use a toggle, and don't rely on something unreliable :)

Chris Naismith • Feb 18 '20

Using both is the preferred option. Support in OS/Browsers for prefers-color-scheme will only increase. Which means if you implement now, you will support more users in the future, rather than doing it later.

Secondly, in initial hit of your site, you can set their preferred theme according to their preferred color schema (dark mode on first hit). If you only rely on a toggle, you force users to use the light mode regardless of their preferred setting.

AlbertoM • Feb 18 '20

Correct, combining both is the best idea.

Patryk • Feb 18 '20

Admittedly, I should have worded this better, as that is what I do. Check for a LocalStorage preference that I set when the user toggles dark mode, and check the schema if the key isn't set.

Moataz Mohammady • Feb 17 '20

Awesome I will try it in my website

AlbertoM • Feb 17 '20

Cool, leave us a link when you implement it!

Supun Kavinda • Feb 17 '20

So, why would you prefer this to CSS variables?

Colum Ferry • Feb 17 '20

CSS Variables for one aren't supported in IE11 : caniuse.com/#feat=css-variables

So for enterprise development you need a ponyfill to support this.

Otherwise, you could certainly set up your theme.css to have a set of CSS Variables you reuse in the rest of your CSS files, then dynamically change between light-theme or dark-theme or other custom themes with JS

AlbertoM • Feb 17 '20

Can you elaborate more?

Bharath Sriraam R R • Feb 17 '20

This is really cool but I was wondering if there would be performance issues when using it with React or frameworks like Angular, etc?

T • Feb 18 '20

Works perfectly in React. I did this previously on a Gatsby project and it works perfectly with no noticeable performance implications. I'm not sure about Angular, but it should be the same.

Bharath Sriraam R R • Feb 18 '20

Great, thank you!

Rahimuddin • Feb 17 '20

I believe instead of maintaining a whole different css file, can't we do it using a single extra class to body (class="dark")? I believe this approach is simple, isn't it? Just a suggestion :)

AlbertoM • Feb 17 '20

Yes you can, it's a totally viable alternative.

KhoPhi • Feb 20 '20

The downside of this method is that your user won't have control over how they want to view your website so I would consider it only if you don't have time or don't want to implement a toggle.

If a user has system-wide dark mode, the chances they'll be okay with their web pages being dark too are high.

As a 100% dark-mode-everything person I am, pages without dark mode irritate me these day.

AlbertoM • Feb 20 '20

Yes, you are right. I just think that giving user's a choice is better.

Kuatyw • Jun 27 '21

My website's default theme is light. O added switch theme button with your code but if i use darkmode when i go another page of website theme is being light and then dark(after 1secons or less) how can i fix it?

Itachi Uchiha • Feb 17 '20

Thanks. You may not need any if block using data attributes. I'm not sure. But this is really great article. Thank you.

Zen • Feb 17 '20

Wow. Awesome. I'll try this in my next projects.

Arsen Ibragimov • Feb 17 '20

Don’t forget to share results with us!

Jennifer M • Aug 28 '21

Interesting method. I already implemented Dark Mode using a cookie and javascript (if cookie is set, insert these rules into a stylesheet) and it works well, even in IE (though you have to do an if/else to not insert certain non-IE rules or an error will stop your page from loading - easy to do for just those rules, though). The user can toggle it on or off using the same button (if it is set, delete the cookie; if it is not set, add the cookie). I also have several other site settings set up this same way (link underline choice for people who are color blind, and background choices).

I found this article when searching for how to set Dark Mode for browser preferences after seeing it as an option in the browser on my new phone. As I have my Dark Mode cookie set to delete after 24 hours (it is more meant for accessibility during a migraine than out of user preference, but of course can also be used as a preference, especially at night), I'm not planning on implementing the browser choice one after reading this article, especially since it would double up on the stylesheets. I'm not sure if one method is better than the other, but since I use the cookie/javascript writing the stylesheets for multiple purposes (and javascript writes my regular background, a random photo background, onto a body::before so it is fixed even on iOS devices), it works best for me. And yes, all the cookies are declared in my Privacy Policy 😝.

Arsen Ibragimov • Feb 17 '20

I want to implement dark mode on my community’s website. I add it to the backlog

Hozefa • Feb 17 '20

How about using CSS variables? They can be changed via javascript also.

Raghavan alias Saravanan Muthu • Feb 17 '20

Hey that is really a super, uber cool tip! I had been thinking of this but not really searched further. It is an easy bite for me. Thank you for sharing the insights!!

Lukastechs.Com • Apr 10 '20

Hi? I'm stuck at saving user preference; I want to make the effect on a site hosted on blogger? any quick tip?

Daniel Quackenbush • Feb 17 '20

Do you find prefers-color-scheme to actually be populated? When I first looked into this, that field was always null.

AlbertoM • Feb 17 '20

It works well on macos Catalina.

Hibrit Usta • May 22 '20

Thank you. Nice article.

diek • Feb 17 '20

Epic guide, thank you!

AlbertoM • Feb 17 '20

Glad you liked it!

Amit Dhamu • Feb 17 '20

I wrote a similar article a few weeks back with React and Gatsby in mind

amitd.co/blog/implementing-dark-mode

AlbertoM • Feb 17 '20

I think having two different files can save you having unnecessary load styles for a theme you don't use. I guess at the end of the day, both will work just fine.

Colum Ferry • Feb 17 '20

The browser should also cache both CSS so the user may only notice a dip in performance on the first time they switch, whilst their cache lives.

Carlos Orelhas • Feb 17 '20

Thanks for sharing! I will try this on my next project.

Barzi • Feb 20 '20

Thank you Alberto.
I'm going to add a dark mode to my side project tonight :)