js 十六进制字符串转换为字节数组

const hexString = "68656c6c6f";
const byteArray = Buffer.from(hexString, 'hex');
console.log(byteArray);

由于浏览器不支持Buffer,使用下面的形式

const hexStringToByteArray = function (hexString) {
    const bytes = new Uint8Array(hexString.length / 2);

    for (let i = 0; i < hexString.length; i += 2) {
        bytes[i / 2] = parseInt(hexString.substr(i, 2), 16);
    }

    return bytes;
}