iterator-prototype-object.html | Explore in Territory

<!doctype html>
<meta charset="utf-8">
<title>Iterator prototype objects</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script>
test(() => {
  const esIteratorPrototype = Object.getPrototypeOf(Object.getPrototypeOf([][Symbol.iterator]()));
  const iteratorProto = Object.getPrototypeOf(new URLSearchParams().entries());
  assert_equals(Object.getPrototypeOf(iteratorProto), esIteratorPrototype);
}, "Has %IteratorPrototype% as prototype");

test(() => {
  const iteratorProto = Object.getPrototypeOf(new URLSearchParams().entries());
  const desc = Object.getOwnPropertyDescriptor(iteratorProto, "next");
  assert_equals(typeof desc.value, "function");
  assert_equals(desc.writable, true);
  assert_equals(desc.enumerable, true);
  assert_equals(desc.configurable, true);
}, "next() exists and is writable, enumerable, and configurable");

test(() => {
  const usp = new URLSearchParams();
  const iteratorProto = Object.getPrototypeOf(usp.entries());

  assert_throws_js(TypeError, () => {
    iteratorProto.next();
  });
  assert_throws_js(TypeError, () => {
    iteratorProto.next.call(undefined);
  });
  assert_throws_js(TypeError, () => {
    iteratorProto.next.call(42);
  });
  assert_throws_js(TypeError, () => {
    iteratorProto.next.call(new Headers().entries());
  });
}, "next() throws TypeError when called on ineligible receiver");

// class string behavior tested in a dedicated file

test(() => {
  const iteratorProto1 = Object.getPrototypeOf(new URLSearchParams().entries());
  const iteratorProto2 = Object.getPrototypeOf(new Headers().entries());
  assert_not_equals(iteratorProto1, iteratorProto2);
}, "Is specific to an interface");
</script>
chromium/third_party/blink/web_tests/external/wpt/webidl/ecmascript-binding/iterator-prototype-object.html
