How to Make an Animated Day and Night Toggle Switch

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

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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:

switching the lights on an off with CSS

Setting Things Up

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

<!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
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We’re going to have three different resources:

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:

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

.toggle:before {
    content: '☀️';
}

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

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

How the scaling animation will work

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

.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
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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.

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

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:

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

        ...
    </body>
</html>
index.html
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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.

.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
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Some important things I would like to point out:

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:

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.jsYou can also toggle the class outside the setTimeout if you want immediate effect
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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:

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
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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.

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
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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.

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

switching the lights on an off with CSS

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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