阅读腾讯出的SDK的源码，发现以下代码(删掉了注释）

const TencentCloudSDKHttpException = require("./exception/tencent_cloud_sdk_exception");
const crypto = require('crypto');

class Sign {
    static sign(secretKey, signStr, signMethod) {
        let signMethodMap = {
            HmacSHA1: "sha1",
            HmacSHA256: "sha256"
        };

        if (!signMethodMap.hasOwnProperty(signMethod)) {
            throw new TencentCloudSDKHttpException("signMethod invalid, signMethod only support (HmacSHA1, HmacSHA256)");
        }
        let hmac = crypto.createHmac(signMethodMap[signMethod], secretKey || "");
        return hmac.update(new Buffer(signStr, 'utf8')).digest('base64')
    }
}
module.exports = Sign;

忽略其中使用废弃的的new Buffer不管， 这本身只是在提供一个函数，根本不需要实例化，为什么非要用class，这算不算滥用class

我的理解是这样写

const TencentCloudSDKHttpException = require("./exception/tencent_cloud_sdk_exception");
const crypto = require('crypto');

function sign(secretKey, signStr, signMethod) {
    let signMethodMap = {
        HmacSHA1: "sha1",
        HmacSHA256: "sha256"
    };

    if (!signMethodMap.hasOwnProperty(signMethod)) {
        throw new TencentCloudSDKHttpException("signMethod invalid, signMethod only support (HmacSHA1, HmacSHA256)");
    }
    let hmac = crypto.createHmac(signMethodMap[signMethod], secretKey || "");
    return hmac.update(Buffer.from(signStr, 'utf8')).digest('base64')
}
module.exports = Sign;

或者保持原代码的调用方式，这样写

const TencentCloudSDKHttpException = require("./exception/tencent_cloud_sdk_exception");
const crypto = require('crypto');

module.exports = {
    sign(secretKey, signStr, signMethod) {
        let signMethodMap = {
            HmacSHA1: "sha1",
            HmacSHA256: "sha256"
        };
    
        if (!signMethodMap.hasOwnProperty(signMethod)) {
            throw new TencentCloudSDKHttpException("signMethod invalid, signMethod only support (HmacSHA1, HmacSHA256)");
        }
        let hmac = crypto.createHmac(signMethodMap[signMethod], secretKey || "");
        return hmac.update(Buffer.from(signStr, 'utf8')).digest('base64')
    }
};