title: How to use readAsArrayBuffer method from FileReader after fetch and get correct size?
body: <p>I want to have access to ArrayBuffer from remote URL. So, I created the function:</p>
  
  <pre><code>        fetch('some url')
              .then(function(response) {
                  const file = new File([response], response.url, {type:'image/jpg'});
                  const reader = new FileReader();
                  reader.readAsArrayBuffer(file);
                  reader.onload = function(e) {
                      const dataURL = reader.result;
                      console.log(dataURL);
                  };
              })
  </code></pre>
  
  <p>And I've got the wrong ArrayBuffer size: ArrayBuffer(17 = length of my Url)  instead of real image size (about 24000, I think). What's the problem here?</p>