const text =
  "An obscure body in the S-K System, your majesty. The inhabitants refer to it as the planet Earth.";

async function digestMessage(message) {
  const encoder = new TextEncoder();
  const data = encoder.encode(message);
  const hash = await crypto.subtle.digest("SHA-256", data);
  return hash;
}

digestMessage(text).then((digestBuffer) =>
  console.log(digestBuffer.byteLength),
);

let key = await window.crypto.subtle.generateKey(
  {
    name: "HMAC",
    hash: { name: "SHA-256" },
  },
  true,
  ["sign", "verify"],
);