title: Manage security on file upload to nodejs
body: <p>I have an image upload view on my client (ember.js) that send the resized image to nodejs rest api;
  it works well but it is easy for someone expert to force upload of a non-resized image;
  I would like to keep the resize process on the client because this allows users to select heavy-weight images, that are resized locally and uploaded only after that, when they are lightweight;</p>
  
  <p>If someone else uses something like this, I'm interested on how it is possible to make this as safe as possible;</p>