title: Confused on blob:url and converting it to base64 in react-dropzone
body: <p>I am using the package react-dropzone (<a href="https://github.com/okonet/react-dropzone" rel="nofollow noreferrer">https://github.com/okonet/react-dropzone</a>) to get images from the user. The user uploads their image and everything is fine, but Im only getting something like "blob:http//blahblah" from it and I need the image to be in base64 png.</p>
  
  <p>my dropzone component: </p>
  
  <pre><code>&lt;Dropzone ref="dropzone" multiple={false} onDrop={this.onDrop.bind(this)} &gt;
    {this.state.files ?&lt;img className="img-responsive" src={this.state.files[0].preview}&gt;&lt;/img&gt;
     : &lt;div&gt;Upload Photo&lt;/div&gt; }
  &lt;/Dropzone&gt;
  </code></pre>
  
  <p>and the drop function that gets the blob url :</p>
  
  <pre><code>onDrop (files ) {
      if ( files.length === 0 ) {
          alert("upload img please")
          return;
      }
      console.log('Received files: ', files);
      this.setState({files:files})
      var blobURL = files[0].preview
      var reader = new FileReader();
      reader.readAsDataURL(blobURL)
    }
  </code></pre>
  
  <p>I would get an error :<code>Uncaught TypeError: Failed to execute 'readAsDataURL' on 'FileReader': parameter 1 is not of type 'Blob'.</code></p>
  
  <p>I think it is because im trying to pass in an object-url that points to a blob, but where would I be able to get blob so I can convert to base64?</p>