navigation-api/navigation-methods/forward-to-pruned-entry.html

<!doctype html>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script>
promise_test(async t => {
  // Wait for after the load event so that the navigation doesn't get converted
  // into a replace navigation.
  await new Promise(resolve => window.onload = () => t.step_timeout(resolve, 0));
  await navigation.navigate("#foo").finished;
  assert_equals(navigation.entries().length, 2);
  await navigation.back().finished;
  assert_equals(navigation.currentEntry.index, 0);

  // Traverse forward then immediately do a same-document push. This will
  // truncate the back forward list, and by the time the traverse commits, the
  // destination key will no longer be present in navigation.entries(). The
  // traverse should abort.
  let forward_value = navigation.forward();
  await navigation.navigate("#clobber").finished;
  assert_equals(navigation.currentEntry.index, 1);
  await promise_rejects_dom(t, "AbortError", forward_value.committed);
  await promise_rejects_dom(t, "AbortError", forward_value.finished);

  // This leaves navigation.entries() in a consistent state where traversing
  // back and forward still works.
  await navigation.back().finished;
  assert_equals(navigation.currentEntry.index, 0);
  await navigation.forward().finished;
  assert_equals(navigation.currentEntry.index, 1);
}, "If forward pruning clobbers the target of a traverse, abort");
</script>