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HTML

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CSS

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JavaScript

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Babel includes JSX processing.

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HTML 

              
                <h1><code>@bramus/style-observer</code> demo</h1>

<h2>Instructions</h2>

<p>Click anywhere on this document to change the <code>background-color</code>. In response, a toast with the new computed value pops-up.</p>

<h2>More info</h2>
<p>This page is a demo for <a href="https://github.com/bramus/style-observer/" target="_top"><code>@bramus/style-observer</code></a>, a <code>MutationObserver</code> for CSS Computed Styles.<br>Go read <a href="https://brm.us/style-observer" target="_top">https://brm.us/style-observer</a> for an introduction and usage instructions.</p>
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CSS 

              
                @import url(https://esm.sh/notyf/notyf.min.css);

body {
	background: lightpink;
	user-select: none;
}

:where(body > *:not(script, .notyf, .notyf-announcer)) {
	background: white;
	display: block;
	padding: 0.2em;
	width: fit-content;
}
pre {
	border: 2px solid lightblue;
	border-left-width: 10px;
	padding: 0.5em;
	font-weight: 700;
	overflow-x: auto;
	max-width: 95vw;
	tab-size: 2;
	background: white;
}

p {
	line-height: 1.34;
}

a {
	color: blue;
}
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JS 

              
                import CSSStyleObserver from "https://esm.sh/@bramus/style-observer@1";
import { Notyf } from "https://esm.sh/notyf";

// Create an instance of Notyf
const notyf = new Notyf({
	ripple: false,
});

// Utility method to show a notification using notyf
const showNotification = (message) => {
	notyf.success(message);
};

// Utility method that generates a random (hex) color
const randomColor = () => '#' + (Math.random() * 0xFFFFFF << 0).toString(16).padStart(6, '0');

// Array with the names of the properties to observe.
// This can be one or more, both regular properties and custom properties
const properties = ['background-color'];

// Create a CSSStyleObserver that tracks the properties.
// Every time one of those properties their computed value changes, the passed in callback gets executed
// Here, the callback shows the new computed value in a notification
const cssStyleObserver = new CSSStyleObserver(properties, (values) => {
  showNotification(`Background color changed to ${values['background-color']}`);
});

// Have the CSSStyleObserver instance observe the `<body>` element
cssStyleObserver.attach(document.body);

// Change the background-color every time you click the document
document.documentElement.addEventListener('click', (e) => {
	document.body.style.setProperty('background-color', randomColor());
});
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999px

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