title: JSZip imgData is not defined
body: <pre class="lang-js prettyprint-override"><code>var zip = new JSZip();
  zip.file("Hello.txt", "Hello World\n");
  
  var img = zip.folder("images");
  img.file(images[0], imgData, {base64: true});
  
  zip.generateAsync({type:"blob"}).then(function(content) {
      // see FileSaver.js
      saveAs(content, "example.zip");
  });
  </code></pre>
  
  <p>Running the code above I get an error: Uncaught ReferenceError: imgData is not defined</p>
  
  <p>How can I make it functional? I tried to find more info regarding it in the documentation but I couldn't find anything. I assume this should just work out of the box?</p>