<!DOCTYPE html>
<meta charset="utf-8">
<title>Interface prototype objects</title>
<link rel="help" href="https://webidl.spec.whatwg.org/#interface-prototype-object">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script>
test(function() {
  // https://webidl.spec.whatwg.org/#create-an-interface-prototype-object
  assert_own_property(Element.prototype, Symbol.unscopables, "Element.prototype has @@unscopables.");
  let unscopables = Element.prototype[Symbol.unscopables];
  assert_equals(typeof unscopables, "object", "@@unscopables is an Object.");
  assert_equals(Object.getPrototypeOf(unscopables), null, "@@unscopables's prototype is null.");
}, "[Unscopable] extended attribute makes @@unscopables object on the prototype object, whose prototype is null.");
</script>
