async function getRoll(serverSeed, serverNonce, clientSeed) {
	const enc = new TextEncoder();
	const key = enc.encode(serverSeed);
	const message = enc.encode(clientSeed + '-' + serverNonce.toString());

	const cryptoKey = await crypto.subtle.importKey(
		'raw',
		key,
		{ name: 'HMAC', hash: 'SHA-512' },
		false,
		['sign']
	);

	const signature = await crypto.subtle.sign('HMAC', cryptoKey, message);
	const hashArray = Array.from(new Uint8Array(signature));
	const hex = hashArray.map(b => b.toString(16).padStart(2, '0')).join('');
	const rollHex = hex.substring(0, 7);
	const number = parseInt(rollHex.replace(/[^a-f0-9]/gi, ''), 16);

	return (number % 100000) + 1;
}

serverSeed = '';
serverNonce = 1;
clientSeed = '';

getRoll(serverSeed, serverNonce, clientSeed).then(roll => console.log('Roll result:', roll));