men232/index.html

## index.html
<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <link rel="stylesheet" href="reset.css">
    <title>How to record a video with JavaScript</title>
  </head>
  <body>
    <video autoplay muted playsinline id="videoLive"></video>
    <script src="main.js"></script>
  </body>
</html>

## main.js
async function main() {
  const buttonStart = document.querySelector("#buttonStart");
  const buttonStop = document.querySelector("#buttonStop");
  const videoLive = document.querySelector("#videoLive");
  const videoRecorded = document.querySelector("#videoRecorded");

  const stream = await navigator.mediaDevices.getUserMedia({
    video: {
      width: { min: 1920, ideal: 1920, max: 1920 },
      height: { min: 1080, ideal: 1080, max: 1080 },
      minFrameRate: '60'
    }
  });

  videoLive.srcObject = stream;

  if (!MediaRecorder.isTypeSupported("video/webm")) {
    console.warn("video/webm is not supported");
  }

  const mediaRecorder = new MediaRecorder(stream, {
    mimeType: "video/webm",
  });

  mediaRecorder.addEventListener("dataavailable", (event) => {
    videoRecorded.src = URL.createObjectURL(event.data);
  });
}

main();

## reset.css
/***
    The new CSS reset - version 1.11.2 (last updated 15.11.2023)
    GitHub page: https://github.com/elad2412/the-new-css-reset
***/

/*
    Remove all the styles of the "User-Agent-Stylesheet", except for the 'display' property
    - The "symbol *" part is to solve Firefox SVG sprite bug
    - The "html" element is excluded, otherwise a bug in Chrome breaks the CSS hyphens property (https://github.com/elad2412/the-new-css-reset/issues/36)
 */
*:where(
    :not(html, iframe, canvas, img, svg, video, audio):not(svg *, symbol *)
  ) {
  all: unset;
  display: revert;
}

body,
html {
  padding: 0;
  margin: 0;
  width: 100%;
  height: 100%;
  background-color: #000;
}

#videoLive {
  position: fixed;
  right: 0;
  bottom: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

/* Preferred box-sizing value */
*,
*::before,
*::after {
  box-sizing: border-box;
}

/* Fix mobile Safari increase font-size on landscape mode */
html {
  -moz-text-size-adjust: none;
  -webkit-text-size-adjust: none;
  text-size-adjust: none;
}

/* Reapply the pointer cursor for anchor tags */
a,
button {
  cursor: revert;
}

/* Remove list styles (bullets/numbers) */
ol,
ul,
menu,
summary {
  list-style: none;
}

/* For images to not be able to exceed their container */
img {
  max-inline-size: 100%;
  max-block-size: 100%;
}

/* removes spacing between cells in tables */
table {
  border-collapse: collapse;
}

/* Safari - solving issue when using user-select:none on the <body> text input doesn't working */
input,
textarea {
  -webkit-user-select: auto;
}

/* revert the 'white-space' property for textarea elements on Safari */
textarea {
  white-space: revert;
}

/* minimum style to allow to style meter element */
meter {
  -webkit-appearance: revert;
  appearance: revert;
}

/* preformatted text - use only for this feature */
:where(pre) {
  all: revert;
  box-sizing: border-box;
}

/* reset default text opacity of input placeholder */
::placeholder {
  color: unset;
}

/* fix the feature of 'hidden' attribute.
 display:revert; revert to element instead of attribute */
:where([hidden]) {
  display: none;
}

/* revert for bug in Chromium browsers
 - fix for the content editable attribute will work properly.
 - webkit-user-select: auto; added for Safari in case of using user-select:none on wrapper element*/
:where([contenteditable]:not([contenteditable="false"])) {
  -moz-user-modify: read-write;
  -webkit-user-modify: read-write;
  overflow-wrap: break-word;
  -webkit-line-break: after-white-space;
  -webkit-user-select: auto;
}

/* apply back the draggable feature - exist only in Chromium and Safari */
:where([draggable="true"]) {
  -webkit-user-drag: element;
}

/* Revert Modal native behavior */
:where(dialog:modal) {
  all: revert;
  box-sizing: border-box;
}

/* Remove details summary webkit styles */
::-webkit-details-marker {
  display: none;
}
	<!DOCTYPE html>
	<html lang="en">
	<head>
	<meta charset="UTF-8" />
	<meta name="viewport" content="width=device-width, initial-scale=1.0" />
	<link rel="stylesheet" href="reset.css">
	<title>How to record a video with JavaScript</title>
	</head>
	<body>
	<video autoplay muted playsinline id="videoLive"></video>
	<script src="main.js"></script>
	</body>
	</html>
	async function main() {
	const buttonStart = document.querySelector("#buttonStart");
	const buttonStop = document.querySelector("#buttonStop");
	const videoLive = document.querySelector("#videoLive");
	const videoRecorded = document.querySelector("#videoRecorded");

	const stream = await navigator.mediaDevices.getUserMedia({
	video: {
	width: { min: 1920, ideal: 1920, max: 1920 },
	height: { min: 1080, ideal: 1080, max: 1080 },
	minFrameRate: '60'
	}
	});

	videoLive.srcObject = stream;

	if (!MediaRecorder.isTypeSupported("video/webm")) {
	console.warn("video/webm is not supported");
	}

	const mediaRecorder = new MediaRecorder(stream, {
	mimeType: "video/webm",
	});

	mediaRecorder.addEventListener("dataavailable", (event) => {
	videoRecorded.src = URL.createObjectURL(event.data);
	});
	}

	main();
	/***
	The new CSS reset - version 1.11.2 (last updated 15.11.2023)
	GitHub page: https://github.com/elad2412/the-new-css-reset
	***/

	/*
	Remove all the styles of the "User-Agent-Stylesheet", except for the 'display' property
	- The "symbol *" part is to solve Firefox SVG sprite bug
	- The "html" element is excluded, otherwise a bug in Chrome breaks the CSS hyphens property (https://github.com/elad2412/the-new-css-reset/issues/36)
	*/
	*:where(
	:not(html, iframe, canvas, img, svg, video, audio):not(svg , symbol )
	) {
	all: unset;
	display: revert;
	}

	body,
	html {
	padding: 0;
	margin: 0;
	width: 100%;
	height: 100%;
	background-color: #000;
	}

	#videoLive {
	position: fixed;
	right: 0;
	bottom: 0;
	width: 100%;
	height: 100%;
	object-fit: cover;
	}

	/* Preferred box-sizing value */
	*,
	*::before,
	*::after {
	box-sizing: border-box;
	}

	/* Fix mobile Safari increase font-size on landscape mode */
	html {
	-moz-text-size-adjust: none;
	-webkit-text-size-adjust: none;
	text-size-adjust: none;
	}

	/* Reapply the pointer cursor for anchor tags */
	a,
	button {
	cursor: revert;
	}

	/* Remove list styles (bullets/numbers) */
	ol,
	ul,
	menu,
	summary {
	list-style: none;
	}

	/* For images to not be able to exceed their container */
	img {
	max-inline-size: 100%;
	max-block-size: 100%;
	}

	/* removes spacing between cells in tables */
	table {
	border-collapse: collapse;
	}

	/* Safari - solving issue when using user-select:none on the <body> text input doesn't working */
	input,
	textarea {
	-webkit-user-select: auto;
	}

	/* revert the 'white-space' property for textarea elements on Safari */
	textarea {
	white-space: revert;
	}

	/* minimum style to allow to style meter element */
	meter {
	-webkit-appearance: revert;
	appearance: revert;
	}

	/* preformatted text - use only for this feature */
	:where(pre) {
	all: revert;
	box-sizing: border-box;
	}

	/* reset default text opacity of input placeholder */
	::placeholder {
	color: unset;
	}

	/* fix the feature of 'hidden' attribute.
	display:revert; revert to element instead of attribute */
	:where([hidden]) {
	display: none;
	}

	/* revert for bug in Chromium browsers
	- fix for the content editable attribute will work properly.
	- webkit-user-select: auto; added for Safari in case of using user-select:none on wrapper element*/
	:where([contenteditable]:not([contenteditable="false"])) {
	-moz-user-modify: read-write;
	-webkit-user-modify: read-write;
	overflow-wrap: break-word;
	-webkit-line-break: after-white-space;
	-webkit-user-select: auto;
	}

	/* apply back the draggable feature - exist only in Chromium and Safari */
	:where([draggable="true"]) {
	-webkit-user-drag: element;
	}

	/* Revert Modal native behavior */
	:where(dialog:modal) {
	all: revert;
	box-sizing: border-box;
	}

	/* Remove details summary webkit styles */
	::-webkit-details-marker {
	display: none;
	}