有可能获得价值和承诺？

Question

下面的代码有效，但是我想在最后query()仅基于返回0或1

return (statusCode === 301 && httpsGet.includes('google')) ? 1 : 0

可能会引入一个全局变量，但是它接错了。

问题

如何在res.statusCode语句中访问try？

const https = require('https');
    
function httpsGet(opts) {
  return new Promise((resolve, reject) => {
    const req = https.get(opts, (res) => {
      let body = '';
      res.on('data', (data) => {
        body += data.toString();
      });

      console.log(res.statusCode);

      res.on('end', () => {
        resolve(body);
      });
    });
    req.on('error', (e) => {
      console.error(e);
      reject(e);
    });
  });
}

async function query(options) {
  options = options || {};
  options.timeout = options.timeout || 0;

  const opt = {
    hostname: 'encrypted.google.com',
    port: 443,
    path: '/',
    method: 'GET',
  };

  opt.agent = new https.Agent(opt);

  try {
    // here I would like to check the status code and search in httpsGet return value
    return await httpsGet(opt);
  } catch (error) {
    console.error(error);
  }
}

(async function () {
  const s = await query({ timeout: 1000 });
  console.log('String: ' + s);
})();

Answer 1

返回的值就是您传递给resolve函数的任何值。

因此，如果您需要状态码，则可以将其添加到返回的对象中。

private enum enRegistersAddr
{
    Volt = 0,
    Current = 20,
    Kw = 140
}


private void Connect_Click(object sender, EventArgs e)
    {
        button1WasClicked = true;
        try
        {
            byte slaveAddress = byte.Parse(ConnectionSetUp.SetValueForAdress);
            
            IModbusMaster masterRTU = ModbusSerialMaster.CreateRtu(serialPort);
            
            ushort numOfPoints = 3;

            ushort[] result = masterRTU.ReadHoldingRegisters  (slaveAddress, 
                  (ushort)enRegistersAddr.Volt, numOfPoints);

            //display result.
            VoltR.Text = string.Empty;

            VoltR.Text = string.Format("{0}", result[0]);
            VoltS.Text = string.Format("{0}", result[1]);
            VoltT.Text = string.Format("{0}", result[2]);

            result = masterRTU.ReadHoldingRegisters  (slaveAddress, 
               (ushort)enRegistersAddr.Current, numOfPoints);

            CurrentR.Text = string.Format("{0}", result[0]);
            CurrentS.Text = string.Format("{0}", result[1]);
            CurrentT.Text = string.Format("{0}", result[2]);

            result = masterRTU.ReadHoldingRegisters  (slaveAddress, 
               (ushort)enRegistersAddr.Kw, numOfPoints);

            Kw_R.Text = string.Format("{0}", result[0]);
            Kw_S.Text = string.Format("{0}", result[1]);
            Kw_T.Text = string.Format("{0}", result[2]);

            
            

        }
        catch (Exception ex)
        {
            timer1.Stop();
            MessageBox.Show(this, ex.Message, "ERROR", MessageBoxButtons.OK, 
               MessageBoxIcon.Error);
        } 

如果您不熟悉解构，那么这两个是相同的：

function httpsGet(opts) {
  return new Promise((resolve, reject) => {
    const req = https.get(opts, (res) => {
      let body = '';
      res.on('data', (data) => {
        body += data.toString();
      });

      console.log(res.statusCode);

      res.on('end', () => {
        resolve({
          body,
          statusCode: res.statusCode, // Here we add status code
        });
      });
    });
    req.on('error', (e) => {
      console.error(e);
      reject(e);
    });
  });
}

async function query(options) {
  options = options || {};
  options.timeout = options.timeout || 0;

  const opt = {
    hostname: 'encrypted.google.com',
    port: 443,
    path: '/',
    method: 'GET',
  };

  opt.agent = new https.Agent(opt);

  try {

    // Unpack return value 
    const { body, statusCode } = await httpsGet(opt);
 
    // Use values
    return (statusCode === 301 && body.includes('google')) ? 1 : 0

  } catch (error) {
    console.error(error);
  }
}

(async function () {
  const s = await query({ timeout: 1000 });
  console.log('String: ' + s);
})();

或

  // Unpack return value 
  const { body, statusCode } = await httpsGet(opt);

  // Use values
  return (statusCode === 301 && body.includes('google')) ? 1 : 0