How to catch HTTP errors in Javascript

Question

I'm writing a Stream Deck plugin in Javascript and I want to log errors to a file. I can't figure out how to capture details of network errors. These errors appear in the debug console, but how can I get them in my own log? The xhr.onerror() method returns not much useful info, just status code 0. I tried adding a window error event listener, but that never triggers. For example this code here:

var xhr = new XMLHttpRequest()
xhr.onerror = function() {console.log('xhr error', arguments)}
window.onerror = function() {console.log('window error', arguments)}
xhr.open('GET', 'http://badurl12345')
xhr.send()

Running this code in the debug console, I see GET http://badurl12345/ net::ERR_NAME_NOT_RESOLVED. But I can't get this info from the error handler.

@dılosürücü - It doesn't work for what the OP is describing. — T.J. Crowder, Aug 30 '20 at 11:14

score 0 · Answer 1 · answered Aug 30 '20 at 11:24

I don't think that level of information is available to the JavaScript code. Even the much-newer fetch API severely restricts the information you get when a network error occurs (such as your name resolution failure example):

A response whose type is "error" is known as a network error.

A network error is a response whose status is always 0, status message is always the empty byte sequence, header list is always empty, and body is always null.

How to catch HTTP errors in Javascript

1 Answers1