Best How To :

Try to wrap it as a Control?

var uploadProgress = function(uploadObj, event) {
  // Do somthing about uploadObj
}

// Target maybe object or string, whatever you want
var Uploader = function(target) {
  var xhr = new XMLHttpRequest();
  var handler = uploadProgress.bind(this, target);
  xhr.upload.addEventListener("progress", handler, false);
  xhr.open("POST", target, true);
  xhr.send(f);
}

The .bind will return a new function, when execute the new function, it'll:

1. Use this here, the Uploader as its context.
2. Execute uploadProgress and pass target as first argument, so the evt given by progess event will be passed to the 2nd param in uploadProgress.