javascript - How to catch net::ERR_CONNECTION_REFUSED

Question

Is there a way to catch failed to load resource: net::ERR_CONNECTION_REFUSED, I've tried:

try {
  $.post('',{},function(res) {
  }).fail(function (xhr, textStatus, errorThrown) { 
    xhr.textStatus = textStatus;
    xhr.errorThrown = errorThrown;
    console.log('fail',xhr);
    // how to get the 'ERR_CONNECTION_REFUSED' or anything else as string?
  });
} catch(e) {
  console.log('catch',e);
}

The fail function could catch, but I got no information about the error, either it is:

• ERR_NAME_NOT_RESOLVED
• ERR_CONNECTION_REFUSED
• ERR_BLOCKED_BY_CLIENT
• ERR_TUNNEL_CONNECTION_FAILED (when using proxy)

or anything else.. the question would be, how to get the kind of error?

Answer 1

I even tried to achieve the goal using javascript XMLHttpRequest()

var xhttp= new XMLHttpRequest();
try{
  xhttp.onreadystatechange = function() {
    console.log(xhttp);
    if (xhttp.readyState == 4 && xhttp.status == 0) {
      alert("Unknown Error Occured. Server response not received.");
    }
  };
  xhttp.open("POST", "http://localhost:8080/data", true);
  xhttp.send();
}catch(e){
  console.log('catch', e);
}