您正在使用restify，它将在调用其方法（post，get ..等）时返回promise。但是您创建的remoterequest方法不会返回promise，您可以使用.then等待。您可以使用async-await或内置的promise返回promise，如下所示：

• 使用promise：

var requestify = require('requestify');

// sends an HTTP request to C and retrieves the response content
function remoterequest(url, data) {
  var returnedvalue;
  return new Promise((resolve) => {
    requestify.post(url, data).then(function (response) {
      var body = response.getBody();
      // TODO use body to send back to the client the number of expected outputs, by setting the returnedvalue variable
    });
    // return at the end of processing
    resolve(returnedvalue);
  }).catch(err => {
    console.log(err);
  });
}

// manages A's request
function manageanotherhttprequest() {
  remoterequest(url, data).then(res => {
    return res;
  });
}

• 使用等待

var requestify = require('requestify');

// sends an HTTP request to C and retrieves the response content
async function remoterequest(url, data) {

  try {
    var returnedvalue;
    var response = await requestify.post(url, data);
    var body = response.getBody();
    // TODO use body to send back to the client the number of expected outputs, by setting the returnedvalue variable
    // return at the end of processing
    return returnedvalue;
  } catch (err) {
    console.log(err);
  };
}

// manages A's request
async function manageanotherhttprequest() {
    var res = await remoterequest(url, data);
    return res;
}

你可以使用sync-request-curl发送同步HTTP请求，这是我在2023年编写的一个库。

• npm：https://www.npmjs.com/package/sync-request-curl
• github：https://github.com/nktnet1/sync-request-curl

它包含了原始sync-request中的一部分功能，但利用了node-libcurl来提高NodeJS的性能。
一个简单的HTTP GET请求可以写如下：

// import request from 'sync-request-curl'; // for ESM
const request = require('sync-request-curl');
const response = request('GET', 'https://ipinfo.io/json');
console.log('Status Code:', response.statusCode);
console.log('body:', response.body.toString());

对于您的情况，您的函数可以按以下同步方式重写：

const request = require('sync-request-curl');

// sends an HTTP request to C and retrieves the response content
function remoterequest(url, data) {
  const response = request('POST', url, { json: data });

  if (response.statusCode === 200) {
    return JSON.parse(response.body.toString());
  } else {
    // handle error
  }
}

// manages A's request
function manageanotherhttprequest() {
  // [...]
  const res = remoterequest(url, data);
  // possible elaboration of res
  return res;
}

希望这对你有帮助：）