Websites/webkit.org/experimental-features.html - WebKit - Git at Google

 <!DOCTYPE html>
 <html>
 <head>
 <title>Experimental features</title>
 <meta name="viewport" content="width=600">
 <style>
 body {
     background-color: #AEBDB4;
     margin: 0;
     font-family: -apple-system, sans-serif;
     font-size: 22px;
 }

 .content {
     width: 480px;
     margin: 30px auto;
     background-color: #D2D2D2;
     border: 1px solid black;
     border-top-width: 5px;
     text-align: center;
 }

 .content h1 {
     font-size: 34px;
     margin: 20px 0;
 }

 .content p {
     margin: 10px 40px;
 }

 .content .test {
     display: flex;
     justify-content: center;
     align-items: center;
     font-size: 22px;
     width: 320px;
     margin: 25px auto;
     height: 70px;
     padding: 0 55px;
     background-color: #e7dd0e;
     border: 2px solid #999309;
     border-radius: 35px;
     background-size: 40px 40px;
     background-position: 15px 15px;
     background-repeat: no-repeat;
     background-image: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 45 45"><circle cx="22.5" cy="22.5" r="22.5" fill="#999309"/><path fill="#e7dd0e" d="M14.58,17.93a7.54,7.54,0,0,1,1.27-4,9.79,9.79,0,0,1,3.71-3.37,11.67,11.67,0,0,1,5.69-1.33,12.15,12.15,0,0,1,5.34,1.12,8.65,8.65,0,0,1,3.58,3,7.44,7.44,0,0,1,1.26,4.17,6.45,6.45,0,0,1-.72,3.11A9.51,9.51,0,0,1,33,22.95q-1,1-3.55,3.26a14.47,14.47,0,0,0-1.14,1.14,4.62,4.62,0,0,0-.64.9,4.4,4.4,0,0,0-.32.81q-.11.41-.34,1.43a2.32,2.32,0,0,1-2.48,2.17,2.54,2.54,0,0,1-1.82-.71A2.78,2.78,0,0,1,22,29.84a7.39,7.39,0,0,1,2-5.28,33,33,0,0,1,2.42-2.3q1.33-1.17,1.93-1.76a6,6,0,0,0,1-1.32,3.2,3.2,0,0,0,.41-1.58,3.68,3.68,0,0,0-1.24-2.81,4.53,4.53,0,0,0-3.2-1.15,4.43,4.43,0,0,0-3.38,1.16A9.23,9.23,0,0,0,20,18.18q-.71,2.36-2.69,2.36a2.64,2.64,0,0,1-2-.82A2.52,2.52,0,0,1,14.58,17.93ZM24.75,40.78A3.28,3.28,0,0,1,22.53,40a2.89,2.89,0,0,1-.95-2.3,3,3,0,0,1,.92-2.21,3.1,3.1,0,0,1,2.25-.9,3.06,3.06,0,0,1,3.11,3.11,2.91,2.91,0,0,1-.94,2.29A3.17,3.17,0,0,1,24.75,40.78Z" transform="translate(-2.5 -2.5)"/></svg>');
 }

 .content .test p {
     margin: 0;
     padding: 0;
 }

 .content .test.enabled {
     background-color: #1fee06;
     border-color: #00aa04;
     background-image: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 45 45"><circle cx="22.5" cy="22.5" r="22.5" fill="#00aa04"/><polyline points="36.13 11.93 16.99 31.07 8.87 22.95" style="fill:none;stroke:#1fee06;stroke-width:7px"/></svg>');
 }

 .content .test.disabled {
     background-color: #fb5207;
     border-color: #ab3903;
     background-image: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 45 45"><circle cx="22.5" cy="22.5" r="22.5" fill="#ab3903"/><path d="M34.57,15.43,15.43,34.57" transform="translate(-2.5 -2.5)" style="fill:none;stroke:#fb5207;stroke-width:7px"/><path d="M15.43,15.43,34.57,34.57" transform="translate(-2.5 -2.5)" style="fill:none;stroke:#fb5207;stroke-width:7px"/></svg>');
 }

 </style>
 <script type="module">
 window.es6modules = true;
 </script>
 <script>
 function testLinkPreload() {
     var link = document.createElement("link");
     return link.relList.supports("preload");
 }

 function testSpringAnimation() {
     return CSS.supports("transition-timing-function", "spring(1 100 10 0)");
 }

 function testVariationFonts() {
     return CSS.supports("font-variation-settings", '"XHGT" 0.7');
 }

 function testES6Modules() {
     return window.es6modules;
 }

 function testSubtleCrypto() {
     return window.crypto.subtle;
 }

 function testWebAnimations() {
     return !!window.Animation;
 }

 function testWebAnimationsCSSIntegration() {
     return !!window.CSSAnimation;
 }

 function testWebGL2() {
     let canvas = document.createElement("canvas");
     return canvas.getContext("webgl2");
 }

 function testWebGPU() {
     return window.gpu;
 }

 function testWebMetal() {
     return window.WebMetalRenderingContext;
 }

 function testWebRTC() {
     return window.RTCPeerConnection;
 }

 function testObjectRest() {
     try {
         eval(`function foo() { let {x, ...rest} = 20; ;({...foo} = 20); };`);
     } catch (e) {
         return false;
     }
     return true;
 }

 function testImageBitmapOffscreenCanvas() {
     return 'createImageBitmap' in window && 'OffscreenCanvas' in window;
 }
 window.addEventListener("load", function () {
     Array.from(document.querySelectorAll(".test")).forEach(element => {
         var enabled = false;
         try {
             var testFunction = window[`test${element.id}`];
             enabled = !!testFunction();
         } catch (e) {
             console.error(e);
         }
         element.classList.add(enabled ? "enabled" : "disabled");
     });
 }, false);
 </script>
 </head>
 <body>
     <div class="content">
         <h1>Experimental Feature Availability</h1>
         <p>Toggle experimental features via the Develop menu (requires reload to take effect).</p>
         <p>These tests do not exercise actual functionality. They are just the most basic check to see if the feature claims to be available.</p>

         <div class="test" id="SpringAnimation"><p>CSS Spring Animations</p></div>
         <div class="test" id="ES6Modules"><p>ES6 Modules in HTML</p></div>
         <div class="test" id="ImageBitmapOffscreenCanvas"><p>ImageBitmap and OffscreenCanvas</p></div>
         <div class="test" id="LinkPreload"><p>Link Preload</p></div>
         <div class="test" id="SubtleCrypto"><p>SubtleCrypto</p></div>
         <div class="test" id="VariationFonts"><p>Variation Fonts</p></div>
         <div class="test" id="WebAnimations"><p>Web Animations</p></div>
         <div class="test" id="WebAnimationsCSSIntegration"><p>Web Animations and CSS Integration</p></div>
         <div class="test" id="WebGL2"><p>WebGL 2.0</p></div>
         <div class="test" id="WebGPU"><p>Web GPU</p></div>
         <div class="test" id="WebMetal"><p>WebMetal</p></div>
         <div class="test" id="WebRTC"><p>WebRTC</p></div>
         <div class="test" id="ObjectRest"><p>ObjectRest</p></div>
     </div>
 </body>
 </html>
	<!DOCTYPE html>
	<html>
	<head>
	<title>Experimental features</title>
	<meta name="viewport" content="width=600">
	<style>
	body {
	background-color: #AEBDB4;
	margin: 0;
	font-family: -apple-system, sans-serif;
	font-size: 22px;
	}

	.content {
	width: 480px;
	margin: 30px auto;
	background-color: #D2D2D2;
	border: 1px solid black;
	border-top-width: 5px;
	text-align: center;
	}

	.content h1 {
	font-size: 34px;
	margin: 20px 0;
	}

	.content p {
	margin: 10px 40px;
	}

	.content .test {
	display: flex;
	justify-content: center;
	align-items: center;
	font-size: 22px;
	width: 320px;
	margin: 25px auto;
	height: 70px;
	padding: 0 55px;
	background-color: #e7dd0e;
	border: 2px solid #999309;
	border-radius: 35px;
	background-size: 40px 40px;
	background-position: 15px 15px;
	background-repeat: no-repeat;
	background-image: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 45 45"><circle cx="22.5" cy="22.5" r="22.5" fill="#999309"/><path fill="#e7dd0e" d="M14.58,17.93a7.54,7.54,0,0,1,1.27-4,9.79,9.79,0,0,1,3.71-3.37,11.67,11.67,0,0,1,5.69-1.33,12.15,12.15,0,0,1,5.34,1.12,8.65,8.65,0,0,1,3.58,3,7.44,7.44,0,0,1,1.26,4.17,6.45,6.45,0,0,1-.72,3.11A9.51,9.51,0,0,1,33,22.95q-1,1-3.55,3.26a14.47,14.47,0,0,0-1.14,1.14,4.62,4.62,0,0,0-.64.9,4.4,4.4,0,0,0-.32.81q-.11.41-.34,1.43a2.32,2.32,0,0,1-2.48,2.17,2.54,2.54,0,0,1-1.82-.71A2.78,2.78,0,0,1,22,29.84a7.39,7.39,0,0,1,2-5.28,33,33,0,0,1,2.42-2.3q1.33-1.17,1.93-1.76a6,6,0,0,0,1-1.32,3.2,3.2,0,0,0,.41-1.58,3.68,3.68,0,0,0-1.24-2.81,4.53,4.53,0,0,0-3.2-1.15,4.43,4.43,0,0,0-3.38,1.16A9.23,9.23,0,0,0,20,18.18q-.71,2.36-2.69,2.36a2.64,2.64,0,0,1-2-.82A2.52,2.52,0,0,1,14.58,17.93ZM24.75,40.78A3.28,3.28,0,0,1,22.53,40a2.89,2.89,0,0,1-.95-2.3,3,3,0,0,1,.92-2.21,3.1,3.1,0,0,1,2.25-.9,3.06,3.06,0,0,1,3.11,3.11,2.91,2.91,0,0,1-.94,2.29A3.17,3.17,0,0,1,24.75,40.78Z" transform="translate(-2.5 -2.5)"/></svg>');
	}

	.content .test p {
	margin: 0;
	padding: 0;
	}

	.content .test.enabled {
	background-color: #1fee06;
	border-color: #00aa04;
	background-image: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 45 45"><circle cx="22.5" cy="22.5" r="22.5" fill="#00aa04"/><polyline points="36.13 11.93 16.99 31.07 8.87 22.95" style="fill:none;stroke:#1fee06;stroke-width:7px"/></svg>');
	}

	.content .test.disabled {
	background-color: #fb5207;
	border-color: #ab3903;
	background-image: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 45 45"><circle cx="22.5" cy="22.5" r="22.5" fill="#ab3903"/><path d="M34.57,15.43,15.43,34.57" transform="translate(-2.5 -2.5)" style="fill:none;stroke:#fb5207;stroke-width:7px"/><path d="M15.43,15.43,34.57,34.57" transform="translate(-2.5 -2.5)" style="fill:none;stroke:#fb5207;stroke-width:7px"/></svg>');
	}

	</style>
	<script type="module">
	window.es6modules = true;
	</script>
	<script>
	function testLinkPreload() {
	var link = document.createElement("link");
	return link.relList.supports("preload");
	}

	function testSpringAnimation() {
	return CSS.supports("transition-timing-function", "spring(1 100 10 0)");
	}

	function testVariationFonts() {
	return CSS.supports("font-variation-settings", '"XHGT" 0.7');
	}

	function testES6Modules() {
	return window.es6modules;
	}

	function testSubtleCrypto() {
	return window.crypto.subtle;
	}

	function testWebAnimations() {
	return !!window.Animation;
	}

	function testWebAnimationsCSSIntegration() {
	return !!window.CSSAnimation;
	}

	function testWebGL2() {
	let canvas = document.createElement("canvas");
	return canvas.getContext("webgl2");
	}

	function testWebGPU() {
	return window.gpu;
	}

	function testWebMetal() {
	return window.WebMetalRenderingContext;
	}

	function testWebRTC() {
	return window.RTCPeerConnection;
	}

	function testObjectRest() {
	try {
	eval(`function foo() { let {x, ...rest} = 20; ;({...foo} = 20); };`);
	} catch (e) {
	return false;
	}
	return true;
	}

	function testImageBitmapOffscreenCanvas() {
	return 'createImageBitmap' in window && 'OffscreenCanvas' in window;
	}
	window.addEventListener("load", function () {
	Array.from(document.querySelectorAll(".test")).forEach(element => {
	var enabled = false;
	try {
	var testFunction = window[`test${element.id}`];
	enabled = !!testFunction();
	} catch (e) {
	console.error(e);
	}
	element.classList.add(enabled ? "enabled" : "disabled");
	});
	}, false);
	</script>
	</head>
	<body>
	<div class="content">
	<h1>Experimental Feature Availability</h1>
	<p>Toggle experimental features via the Develop menu (requires reload to take effect).</p>
	<p>These tests do not exercise actual functionality. They are just the most basic check to see if the feature claims to be available.</p>

	<div class="test" id="SpringAnimation"><p>CSS Spring Animations</p></div>
	<div class="test" id="ES6Modules"><p>ES6 Modules in HTML</p></div>
	<div class="test" id="ImageBitmapOffscreenCanvas"><p>ImageBitmap and OffscreenCanvas</p></div>
	<div class="test" id="LinkPreload"><p>Link Preload</p></div>
	<div class="test" id="SubtleCrypto"><p>SubtleCrypto</p></div>
	<div class="test" id="VariationFonts"><p>Variation Fonts</p></div>
	<div class="test" id="WebAnimations"><p>Web Animations</p></div>
	<div class="test" id="WebAnimationsCSSIntegration"><p>Web Animations and CSS Integration</p></div>
	<div class="test" id="WebGL2"><p>WebGL 2.0</p></div>
	<div class="test" id="WebGPU"><p>Web GPU</p></div>
	<div class="test" id="WebMetal"><p>WebMetal</p></div>
	<div class="test" id="WebRTC"><p>WebRTC</p></div>
	<div class="test" id="ObjectRest"><p>ObjectRest</p></div>
	</div>
	</body>
	</html>