title: how to preprocess a local CSV file before upload
body: <p>I'm working on a Django project where the user is able to upload a CSV file. 
  What I want to do is that user can edit the local csv file , and apply the changes he wants to the csv values before upload.
  I have tried the javascript FileReader API but it seams that it does not offer the editing possibility. 
  Is there a way to do so ? Is there some tutorials that can help ? Thank you </p>