title: Tampermonkey - save blob with GM_download?
body: <p>I was wondering if there's a way to use Tampermonkey GM_download to save a blob to local filesystem without showing "save as"-window.</p>
  
  <p>So you can automatically save a canvas image (instead of an url). I tried it like this:</p>
  
  <pre class="lang-js prettyprint-override"><code>var blob = canvas.toDataURL({ format: 'png' });
  arg = { 
    url: blob,
      name: "CustomFileName.png"
  };
  GM_download(arg);
  </code></pre>
  
  <p>But unfortunately that does not work. Does somebody have any ideas?</p>