fetch/api/request/url-encoding.html

<!doctype html>
<meta charset=windows-1252>
<title>Fetch: URL encoding</title>
<script src=/resources/testharness.js></script>
<script src=/resources/testharnessreport.js></script>
<script>
const expectedURL = new URL("?%C3%9F", location.href).href;
const expectedURL2 = new URL("?%EF%BF%BD", location.href).href;
test(() => {
  let r = new Request("?\u00DF");
  assert_equals(r.url, expectedURL);

  r = new Request("?\uD83D");
  assert_equals(r.url, expectedURL2);
}, "URL encoding and Request");

promise_test(() => {
  return fetch("?\u00DF").then(res => {
    assert_equals(res.url, expectedURL);
    return fetch("?\uD83D").then(res2 => {
      assert_equals(res2.url, expectedURL2);
    });
  });
}, "URL encoding and fetch()");
</script>