process submitted files, and only upload the processed versions

gistfile1.js

function process(file) {
  var processedVersion = /*do stuff and return a processed version */
  
  processedVersion.processedByMyApp = true;
  uploader.addBlobs(processedVersion);
}

var uploader = new qq.FineUploader({
  request: {
    endpoint: "/uploads"
  },
  
  callbacks: {
    onSubmit: function(id) {
      var file = this.getFile(id);
      if (!file.processedByMyApp) {
        process(file);
        return false;
      }
    }
  }
});