why xhr cannot set response type when async is false
<pre><code>var xhr = new XMLHttpRequest();

xhr.responseType = 'json';

xhr.open('GET', '/api/album/category', false);
</code></pre>

<p>//ERROR: VM829:1 Uncaught DOMException: Failed to execute 'open' on 'XMLHttpRequest': Synchronous requests from a document must not set a response type.at :1:5(anonymous function) @ VM829:1</p>

<p>why xhr cannot set response type when async is false?????</p>