Writing below code, I am expecting that error occurred during server starting or starting of listening will be catched in the catch block.

const HTTP = require("http");

try {

  HTTP.
    createServer((request, response) => {
      console.log(request);
      console.log(response);
    }).
    listen(3000, () => { console.log("started") });

} catch (error) {

  console.error(error);

}

Actually, it did not happen. For example, if execute two instances of above file, the second one will crush with

Error: listen EADDRINUSE: address already in use :::3000

CodePudding user response：

You can use

process.on('uncaughtException', function(e){
    console.log(e);
});

To handle uncaught exceptions. Any unhandled exception from the web server could be caught like this.

CodePudding user response：

You need to listen on the error event to get the error message.

server.on('error', (err) => {
  throw err;
});

More complete code

const net = require('net');
const server = net.createServer((c) => {
  // 'connection' listener.
  console.log('client connected');
  c.on('end', () => {
    console.log('client disconnected');
  });
  c.write('hello\r\n');
  c.pipe(c);
});


// NOTICE THIS CODE BLOCK
server.on('error', (err) => {
  throw err;
});

server.listen(8124, () => {
  console.log('server bound');
});

As you can see server.on('error') is listening to the emitted error and throwing it back. You can wrap it in try catch block to get the error.

CodePudding user response：

An alternative to using server.on and listening to the event yourself is to make a promise that waits for the listening and error events.

const HTTP = require("http");
const { once } = require("events");

(async function() {
  try {

    const server = HTTP.
      createServer((request, response) => {
        console.log(request);
        console.log(response);
      });
    server.listen(3000, () => { console.log("started") });
    await once(server, 'listening');
    console.log('started (2)');

  } catch (error) {

    console.error(error);

  }
})();

Note:

1. You can only use await outside of a function ("top level await") in some cases, so this example is wrapped in (async function() {})()
2. once will catch errors while listening has not been emitted yet. As soon as listening is emitted, the code continues.
3. Read more about events.once here.