I understand the workflow of cancelling an ongoing request with AbortSignal, which is to pass it to the options:

const res = await fetch('/endpoint', { signal });
const data = await res.json();

However, what happens if the signal is cancelled after the request itself has finished, but before the data has been parsed? Like this:

const res = await fetch('/endpoint', { signal });
// Cancel signal here
const data = await res.json();

My tests in Firefox, Chrome and Safari show that it will be properly cancelled and throw during that res.json(), but is it the official behavior?

const log = (...text) => document.body.insertAdjacentHTML('beforeend', `${text.join(' ')}<br />`);

(async () => {
  try {
    const controller = new AbortController();
    const signal = controller.signal;

    const res = await fetch('https://swapi.dev/api/films/2/', { signal });
    log('Request:', signal.aborted);
    controller.abort();
    log('Before:', signal.aborted);
    const data = await res.json();
    log('After:', signal.aborted);
  } catch (error) {
    log('Cancelled:', error.name);
  }
})();

// Request: false
// Before: true
// Cancelled: AbortError

From the output we can see it properly throws on res.json(), it never reaches the After step, and it's thrown with an AbortError.