trusted-types/block-Document-execCommand.html

<!DOCTYPE html>
<meta http-equiv="Content-Security-Policy" content="require-trusted-types-for 'script'">
<link rel="author" title="Daniel Vogelheim" href="mailto:vogelheim@chromium.org"></link>
<link rel="help" href="https://w3c.github.io/trusted-types/dist/spec/"></link>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<body>
<script>
  // Tests that certain execCommand commands will observe Trusted Types if
  // it's enforced.
  const commands = [ "insertHTML", "paste" ];
  const tt_commands = [ "insertHTML" ];

  // A pass-through policy for testing.
  const a_policy = trustedTypes.createPolicy("a policy", {"createHTML": x => x});

  for (const command of commands) {
    const requires_tt = tt_commands.includes(command);

    // Test that execCommand with String throws, but only for commands that
    // require TT.
    if (requires_tt) {
      test(t => {
        assert_throws_js(TypeError, _ => document.execCommand(command, false, "<em>Hello World</em>"));
      }, `Document.execCommand("${command}") throws.`);
    } else {
      test(t => {
        document.execCommand(command, false, "<em>Hello World</em>");
      }, `Document.execCommand("${command}") works as usual."`);
    }
    // Test that execCommand succeeds with a TrustedHTML argument.
    test(t => {
      document.execCommand(command, false, a_policy.createHTML("<em>Hello World</em>"));
    }, `Document.execCommand("${command}") works with a TrustedHTML argument.`);
  }

  // Test that with a default policy, all comamnds will work again.
  trustedTypes.createPolicy("default", {"createHTML": (x, _, sink) => {
    assert_equals(sink, 'Document execCommand');
    return x;
  }});

  for (const command of commands) {
    test(t => {
      document.execCommand(command, false, "<em>Hello World</em>");
    }, `Document.execCommand("${command}") works as usual with a default policy.`);
  }
</script>