The reason read-only property returns a JavaScript value that indicates the abort reason.

The property is undefined when the signal has not been aborted. It can be set to a specific value when the signal is aborted, using AbortController.abort() or AbortSignal.abort(). If not explicitly set in those methods, it defaults to "AbortError" DOMException.

A JavaScript value that indicates the abort reason, or undefined, if not aborted.

In the following snippet, we create a new AbortController object, and get its AbortSignal (available using the signal property). Later on, using the aborted property, we check whether or not the signal has been aborted, and log the abort status and reason to the console.

const controller = new AbortController();
const signal = controller.signal;

// …

if (signal.aborted) {
  if (signal.reason) {
    console.log(`Request aborted with reason: ${signal.reason}`);
  } else {
    console.log("Request aborted but no reason was given.");
  }
} else {
  console.log("Request not aborted");
}

• Fetch API