A small trick to check if youtube video exist with its id.

ValidateYoutubeVideoId.js

function validVideoId(id) {
		var img = new Image();
		img.src = "http://img.youtube.com/vi/" + id + "/mqdefault.jpg";
		img.onload = function () {
			checkThumbnail(this.width);
		}
	}

	function checkThumbnail(width) {
		//HACK a mq thumbnail has width of 320.
		//if the video does not exist(therefore thumbnail don't exist), a default thumbnail of 120 width is returned.
		if (width === 120) {
			alert("Error: Invalid video id");
		}
	}

I just want to add the GET and HEAD notwithstanding, for in-browser use your original code is key because of cross-origin restrictions. Thanks again!

I found another one, it returns a smaller image:
"http://img.youtube.com/vi/" + id + "/default.jpg"

This will work EXCEPT for a very small number of Youtube IDs that do exist, but nevertheless lack a preview image and have that 120px-wide one instead. Typically this is because the account owner had deleted them then undeleted them, and sometimes the preview images don't come back. An example is this one: "iUjUnrpsp6I".
I just remove them from the results manually like so, but maybe there's a better way:

function validVideoId(id) {
var img = new Image();

	if (id != 'iUjUnrpsp6I') {
		img.src = "http://img.youtube.com/vi/" + id + "/mqdefault.jpg";
		img.onload = function () {
			checkThumbnail(this.width);
		}
	}
}

This has saved my sanity, thank you for this! My codebase is in PHP so I took the liberty of taking the principle and rewriting it. I may as well paste here what I did for if anyone needs it!:

function getYouTubeThumbnailDimensionsByID(string $id): Array {
    $image_curl = curl_init();
    curl_setopt($image_curl, CURLOPT_URL, "http://img.youtube.com/vi/$id/mqdefault.jpg");
    curl_setopt($image_curl, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($image_curl, CURLOPT_HTTPAUTH, CURLAUTH_ANY);
    $image_result = curl_exec($image_curl);

    $image = imagecreatefromstring($image_result);

    return [
        "x" => imagesx($image),
        "y" => imagesy($image)
    ];
}

Then of course just check if x == 120.

There are exceptions, but it's still the best way to simply check in Javascript. I tried to compare sha1 hash values with difficulty.
Thank you.

Thank you for the trick, saved my day

you beauty! I've found nothing else that works.

thanks man it works

my approach is this btw :
im using venilla js.

const is_valid_ytd_video = async (id) => {
let response = await axios.request("https://www.youtube.com/embed/" + id)
return response.data.toLowerCase().includes("Video unavailable".toLowerCase());
}