Fetching Particle.publish for output in an html textbox

[LandonM25]

For a group final project I'm looking to fetch particle.publish statements from the photon and print them in a log box on an html site. The project works as a security system for a house in a very basic sense. You can toggle the system to armed or unarmed from the website, if armed and motion is detected, the door is locked with a servo motor. The issue I'm running into is ouputting the detection of motion with a timestamp on the website so the user can see it.
The method I was recommended was subscribing to the event like so:

String latestEvent = "No events yet";

  Particle.variable("latestEvent", latestEvent);
  Particle.subscribe("", handleEvent, MY_DEVICES);

and with the function

void handleEvent(const char *event, const char *data)
{
  String timeStr = Time.format(Time.now(), "%H:%M:%S");
  latestEvent = "[" + timeStr + "] " + String(event) + ": " + (data ? String(data) : "");
}

Then, to fetch it from the cloud in the html using

function pollLatestEvent() {
            fetch(`https://api.particle.io/v1/devices/${deviceId}/latestEvent?access_token=${accessToken}`)
                .then(res => res.json())
                .then(data => {
                    const latest = data.result;
                    if (logLines[0] !== latest) {
                        logLines.unshift(latest);
                        if (logLines.length > MAX_LOG_LINES) logLines.pop();
                        logBox.value = logLines.join("\n");
                    }
                })
                .catch(err => {
                    console.error("Failed to fetch event:", err);
                });
        }

        setInterval(pollLatestEvent, 2000);

However the website is not able to fetch the statement and returns an error every two seconds:
Failed to fetch events: ReferenceError: res is not defined at SecurITY.html:88:13

Any suggestions? The tutoring system for this class has been of no help due to lack of available office hours and email response times so I'm trying anything.

[rickkas7]

Which line is line 88?

You can no longer put the access token as a query parameter in a GET request. See sending your access token.

You can't subscribe to an empty event name. There is no way to subscribe to all events on a device, it needs to have a least a prefix of a name.

[ericpietrowicz]

Hey @LandonM25 it seems like you're getting a Reference Error when trying to call res on line 88 of your script. It's possible you have a scoping issue or are calling res before it's defined.

[LandonM25]

line 88 is the beginning of this if statement
if (logLines[0] !== latest) {
logLines.unshift(latest);
if (logLines.length > MAX_LOG_LINES) logLines.pop();
logBox.value = logLines.join("\n");
}