src/third_party/web_platform_tests/XMLHttpRequest/response-data-blob.htm

<!DOCTYPE html>
<html>
<head>
    <link rel="help" href="https://xhr.spec.whatwg.org/#the-send()-method" />
    <link rel="help" href="https://xhr.spec.whatwg.org/#the-responsetype-attribute"  data-tested-assertations="following::ol[1]/li[4]"/>
    <link rel="help" href="https://xhr.spec.whatwg.org/#the-response-attribute"  data-tested-assertations="following::a[contains(@href,'#blob-response-entity-body')]/.." />
    <script src="/resources/testharness.js"></script>
    <script src="/resources/testharnessreport.js"></script>
    <title>XMLHttpRequest: The response attribute: Blob data</title>
</head>

<body>
    <div id="log"></div>

    <script type="text/javascript">
        var test = async_test();

        test.step(function()
        {
            var xhr = new XMLHttpRequest();
            var content = "Hello";
            var blob;

            xhr.onreadystatechange = function()
            {
                if (xhr.readyState == 4)
                {
                    test.step(function()
                    {
                        blob = xhr.response;
                        assert_equals(xhr.response, xhr.response,
                                      "Response should be cached");
                        assert_true(blob instanceof Blob, 'blob is a Blob');

                        var reader = new FileReader();
                        reader.onload = function()
                        {
                            test.step(function()
                            {
                                assert_equals(reader.result, content);
                                test.done();
                            });
                        };
                        reader.readAsText(blob);
                    });
                }
            }

            xhr.open("GET", "./resources/content.py?content=" + content, true);
            xhr.responseType = "blob";
            xhr.send();
        });
    </script>
</body>
</html>