How to Make an Animated Day and Night Toggle Switch

With vanilla Javascript and CSS

Ferenc Almasi •

2021 11 November •

8 min read

Learn how you can make an animated day and night toggle switch with CSS to switch between a light and a dark theme of your app.

Providing an option for your users to toggle between a dark and light theme can be a great way to let them:

Reduce the brightness of your site at night
Save battery power when low
Or just provide a different version of your site for their preference

We will look at how you can create an animated toggle button with only CSS. We will also be looking at how you can use CSS variables to define different color schemes. And by the end of this tutorial, you will be able to build a light switcher, like the one below:

Setting Things Up

Create an index.html file at the root of your project and fill it with the following:

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<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8" />
        <meta name="viewport" content="width=device-width, initial-scale=1.0" />
        <title>Day & Night Toggle Switch</title>

        <link rel="stylesheet" href="colors.css" />
        <link rel="stylesheet" href="styles.css" />
    </head>
    <body>
        <span class="toggle"></span>

        <div class="wrapper">
            <h1>Day & Night</h1>
            <h2>Toggle Switch</h2>
            <p>Created with CSS</p>
            <span>Using <b>CSS</b> variables</span>
        </div>

        <script src="toggle.js"></script>
    </body>
</html>

index.html

We’re going to have three different resources:

colors.css will hold all the color definitions
styles.css will hold the styles for the .toggle as well as the .wrapper
toggle.js will hold a click event listener for toggling classes

Let’s go over each and see what we need to add for them. At first, we want to create the toggle.

Creating The Toggle

Open up your styles.css and define the following styles for the .toggle:

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.toggle {
    position: absolute;
    cursor: pointer;
    top: 20px;
    right: 25px;
    font-size: 150%;
}

.toggle:before {
    content: '☀️';
}

.toggle.active:before {
    content: '🌒';
}

styles.css

I have to mention two important things here. First, you should set cursor to pointer to provide visual feedback to the user that the element can be interacted with. Secondly, we want to change the icon — which is in the content of the before pseudo-element — based on an .active class.

toggling the active class in DevTools — Adding the active class in DevTools toggles the icon

Of course, we don’t want to toggle the class through DevTools, so let’s add the event listener in JavaScript.

Adding the Event Listener

For this to work, we need the following function attached to the .toggle element.

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document.querySelector('.toggle').addEventListener('click', function() {
    this.classList.toggle('active');
});

toggle.js

At this point, we are able to toggle the icon on and off. To spice things up, let’s also add some animation.

toggling the class through JavaScript — Clicking the icon toggles the class

Adding the Scaling Animation

The animation will work in the following way: We scale the icon down to 0. When it hits 0, the icon is essentially invisible. This is when we need to toggle the .active class to change the icon. Then we scale the icon back to its original size.

To achieve this, add the following to your style.css file:

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.toggle.animate {
    animation: animate .3s cubic-bezier(0.4, 0.0, 0.2, 1);
}

@keyframes animate {
    0%   { transform: scale(1); }
    50%  { transform: scale(0); }
    100% { transform: scale(1); }
}

style.css

We will animate the icon in 300ms to make the animation fast. To handle this through JavaScript, we will also need to modify our event listener a bit.

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 document.querySelector('.toggle').addEventListener('click', function() {
+    this.classList.add('animate');
    
+    setTimeout(() => {
        this.classList.toggle('active');
+    }, 150);
    
+    setTimeout(() => this.classList.remove('animate'), 300);
});

toggle.diff

First, we need to add the animate class to start the animation. At the half of the animation — which is set to 300ms in styles.css, so we need to use 150 here — we toggle the .active class. At the end of the animation, we can remove the .animate class.

animating the icon with transform: scale — Animating the icon with transform: scale

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Adding The Ripple Effect

To make the background transition feel like a wave, we can use a CSS trick instead of changing the background-color property. We will animate the box-shadow instead. For this to work, we need a new element. Add the following line to your index.html file:

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<!DOCTYPE html>
<html lang="en">
    <head>
        ...
    </head>
    <body>
        <span class="toggle"></span>
        <span class="wave"></span>

        ...
    </body>
</html>

index.html

Since we are already doing some animation on the .toggle element, we don’t want to animate its box-shadow, otherwise, we would get weird effects. That is why we need to use a separate element. Let’s define the styles associated with the it.

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.wave {
    position: absolute;
    top: 35px;
    right: 40px;
    border-radius: 100%;
    width: 2px;
    height: 2px;
    display: block;
    z-index: -1;
    box-shadow: 0 0 0 0 #212121;
    transition: box-shadow .3s cubic-bezier(0.4, 0.0, 0.2, 1);
}

.wave.active {
    background: #212121;
    box-shadow: 0 0 0 9999px #212121;
}

styles.css

Some important things I would like to point out:

The .wave needs to be positioned exactly in the middle of the icon, so it starts growing from its inside.
Its border-radius needs to be set to 100% to be circular.
Why the 2px for width and height? This is the smallest size on which border-radius works.
You’ll also need to set z-index to -1 to make sure it doesn’t cover other elements on the page.
I set the background-color purposefully to black on the .active state to prevent a white dot showing in place of the icon, when it’s invisible.

changing the box shadow on the wave element

If we start changing the size of the box-shadow, we can see that the background slowly turns into darkness. Let’s also update the event listener in JavaScript:

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document.querySelector('.toggle').addEventListener('click', function() {
    this.classList.add('animate');
   
    setTimeout(() => {
        this.classList.toggle('active');
        document.querySelector('.wave').classList.toggle('active');
    }, 150);
   
    setTimeout(() => this.classList.remove('animate'), 300);
});

toggle.js

You can also toggle the class outside the setTimeout if you want immediate effect

toggling the toggle with wave effect applied — I’ve changed the transition’s speed to 1s to prevent the GIF making the animation look laggy

Adding Color Definitions

All that’s left to do is to add the color definitions so we have different styles for different themes. Open up your colors.css file and fill it with the following content:

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html {
    --background: #212121;
    --box-shadow: #000;
    --text: #FFF;
    --text-faded: #CCC;
    --badge-background: #162F48;
    --badge-color: #0B81D0;
}

.theme-dark {
    --background: #FFF;
    --box-shadow: #CCC;
    --text: #212121;
    --text-faded: #333;
    --badge-background: #FFDA44;
    --badge-color: #d35400;
}

colors.css

As you can see, we don’t have anything, besides the colors. All we are doing here is rewriting the CSS variables for different themes. Again, we want to toggle a class, but this time, on the HTML element itself.

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document.querySelector('.toggle').addEventListener('click', function() {
    this.classList.add('animate');
    
    setTimeout(() => {
        this.classList.toggle('active');
        document.querySelector('.wave').classList.toggle('active');
        document.documentElement.classList.toggle('theme-dark');
    }, 150);
    
    setTimeout(() => this.classList.remove('animate'), 300);
});

toggle.js

This is the last thing to add in the .toggle event listener. So how would you use these variables inside CSS? Instead of hard-coding colors, you can use the var function to retrieve the values from the defined colors.

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.wrapper {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    padding: 20px;
    background: var(--background);
    color: var(--text);
    border-radius: 5px;
    box-shadow: 0 3px 0 0 var(--box-shadow);
    transition: all .3s cubic-bezier(0.4, 0.0, 0.2, 1);
}

styles.css

Make sure you add a transition property to smoothly animate the colors. All that’s left to do is to test everything out.

Summary

In roughly 10 lines of JavaScript code, you are able to create a day-night toggle switch to help your users in various ways. It’s easy to implement and highly customizable. With the help of CSS variables, you can also create multiple themes by simply adding another class with another set of color schemes.

If you would like to experiment with the finished project, you can clone it from GitHub. Thank you for taking the time to read this article. Happy coding!

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Courses

How to Make an Animated Day and Night Toggle Switch

Setting Things Up

Creating The Toggle

Adding the Event Listener

Adding the Scaling Animation

Adding The Ripple Effect

Adding Color Definitions

Summary

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How to Make an Animated Day and Night Toggle Switch

Setting Things Up#

Creating The Toggle#

Adding the Event Listener#

Adding the Scaling Animation#

Adding The Ripple Effect#

Adding Color Definitions#

Summary#

Rocket Launch Your Career

Courses

CSS - The Complete Guide (including Flexbox, Grid and Sass)

The HTML & CSS Bootcamp

The Creative HTML5 & CSS3 Course

Recommended

How to Make a Real-Time Chat App With Socket.io

How To Easily Fetch Data With React Hooks

How To Make Dynamic Backgrounds With The CSS Paint API

Setting Things Up

Creating The Toggle

Adding the Event Listener

Adding the Scaling Animation

Adding The Ripple Effect

Adding Color Definitions

Summary