Node.js Express 响应在 Promise 解决之前结束

Question

Executing following code on Node.js with Express, but it does not return anything. It looks like res.send does not work from within promise.then(); Looks like it already returned back to the caller before promise resolve(); What I'm doing wrong? According to examples, it should work. Thanks.

    const express = require('express');
    const app = express();

    app.get('/test', (req, res, next) => {
      res.send("Good");  // Works Just Fine , but I dont need to return here
      getMessage().then(function(data){
          console.log("I'm here"); // Message works
          res.send("Good");  // Does not Work 
        }).catch(function(error){
          res.send("Error");
      });
    });

    function getMessage(){
        return new Promise(function(resolve, reject){        
           setTimeout(function() {
            resolve();
    }, 3000);
        });    
    }
  app.listen(PORT, () => {
console.log("run");
});

Answer 1

Please add following code to your app: Refer Here

This app starts a server and listens on port 8080 for connections

app.listen(8080, function () {
  console.log('Example app listening on port 8080!')

})

Answer 2

You need to listen on a port for the express server to run.

const express = require('express');
const app = express();
const port = process.env.PORT || 3000;

app.get('/test', (req, res, next) => {
  getMessage().then(function(data){
      res.send("Good");  
    }).catch(function(error){
      res.send("Error");
  });
});

function getMessage() {
    return new Promise((resolve, reject) => {        
       setTimeout(function() {
        resolve();
       }, 3000);
    });    
}

app.listen(port, () => console.log(`App listening at http://localhost:${port}`));

Answer 3

问题出在我用于测试的 Postman 中的请求超时设置中。

Answer 4

Remove the first

res.send('good');

or you could res.write() first then the message should be concatenated when res.send()

res.write('good')

res.send() closes the connection between the server and client therefore using res.write() will write the message and when res.send() is sent all the written messages (using res.write()) are sent back to the client called

IN SHORT
res.write() can happen several times
res.send() happens once only per request