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 window.crypto.subtle.digest("SHA-256", data);
  return hash;
}

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

将摘要转换为十六进制字符串

摘要以 ArrayBuffer 的形式返回，但为了进行比较和显示，通常会使用十六进制（hex）字符串的形式表示。此示例计算摘要，然后将 ArrayBuffer 转换为十六进制字符串：

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 msgUint8 = new TextEncoder().encode(message); // 编码为（utf-8）Uint8Array
  const hashBuffer = await window.crypto.subtle.digest("SHA-256", msgUint8); // 计算消息的哈希值
  const hashArray = Array.from(new Uint8Array(hashBuffer)); // 将缓冲区转换为字节数组
  const hashHex = hashArray
    .map((b) => b.toString(16).padStart(2, "0"))
    .join(""); // 将字节数组转换为十六进制字符串
  return hashHex;
}

digestMessage(text).then((digestHex) => console.log(digestHex));

规范

Specification
Web Cryptography API # SubtleCrypto-method-digest

浏览器兼容性

BCD tables only load in the browser

备注：Chrome 60 添加了对非 TLS 连接禁用 crypto.subtle 的特性。