Skip to content

Instantly share code, notes, and snippets.

Created Nov 1, 2016
What would you like to do?


The last word on uploading files.

"Uppy is a sleek, modular file uploader that integrates seemlessly with any framework. It's fast, easy to use and let's you worry about more important problems than building a file uploader.


  • capabilities is mentioned before explained
  • capabilities could also be confused with the crypto equivalent - different meaning tho it's cool probably
  • capabilities also seem enumerable - enumerating them is probably worth it
  • addFile() mentions plugin types - shoulda been mentioned sooner
  • consider using hemingway
  • or run this:

where alex >/dev/null
[ $? -eq 0 ] || npm i -g alex

where write-good >/dev/null
[ $? -eq 0 ] || npm i -g write-good

where aspell >/dev/null
[ $? -eq 0 ] || brew install aspell

printf '[aspell] running\n'
aspell check "$1"
printf '[write-good] running\n'
write-good "$1"
printf '[alex] running\n'
alex "$1"


  • file size cuts rely on dead code elimination rather than specific imports
  • terminology isn't always clear
  • mash up of different API types (event emitter, external state, prototypes)
  • not sure how to create new plugins


  • import with / is not great for file sizes; not necessarily an issue with rollup but that's not for everyone
  • new can be unwieldy - use if (!(this insteanceof Foo))
  • Core is an odd name; the thing being used is the uppy file transfer framework; all instances of Core in code will look odd in the light of a real application I reckon
  • The core setup discourages third party integrations; they'd be imported differenty which leaves others to feel a bit lackluster
  • feels use of prototypes is leaking into API design - it's an implementation detail, really


  • found it unintuitive they plugins were called by uppy rather than initialized by the user
  • found it unintuitive args are passed later
  • feels technical implementation is leaking into plugin design
  • using closures is fine and given it's not in the hot path it's fast enough
  • if there's only a single mandatory argument, it makes sense to make it the first arg passed
    • breaks the current single opts arg passing paradigm
    • makes for a more intuitive API
    • again: not hot path so it's all cool


state [patch] -> uppy -> state [complete]
const Progress = require('uppy/progress')
const dnd = require('uppy/drag-and-drop')
const tus10 = require('uppy/tus10')
const uppy = require('uppy')

const upload = uppy()

upload.use(function (state, cb) {
  const newState = changeState
  cb(null, newState)

upload.use(Progress({ appendChild: 'body' }))

  namespace: 'uppy',
  reducers: {
    update: function(state, data) {
      return data
    addFile: function (state, data) {
      return state.files.push(data)
  state: {}

function (state, prev, send) {
  const opts = { thumbnails: false }
  const el = upload(opts, (err, state) => {
    if (err) throw err
    send('update', state)

el.set({ my: 'state' })
  • so .use() would detect the .plugin value on any given value passed in and use that as a plugin - allows for using a result as both a plugin and DOM render target without needing to introduce more keywords. - Just pass it in; similar to how pull-stream does it - lil bit of polymorphism is cool


We're not Java - heavy taxonomy is not cool. Uppy should be allowed to modify state in whichever way it wants. When all updates are done, callback is called with new state which can be used by any other framework if desired.

Default state:

{ files: [] }


{ files: [ { file: File, thumbnail: Image }] }
// or
{ files: [], thumbnails: { filename: Image } }
  • getState - remove and make part of callback
  • setState - rename to set(), partial setting of vars is cool
  • updateAll() - if state is flushed on each set, this is not needed
  • updateMeta() - make files part of state
  • addFile() - just push to files array OR perhaps we do need a special file adding API - it could make sense; matter of taste and what a file looks like internally
  • capabilities - not needed; just read out state
  • log - not needed; hooks that tie into lifecycle events might be more interesting - any more debuggint than that feels off
  • .on(), .emit(), .emitter - not needed; use state
uppy.set({ files: [ File ] })


  • Drag and Drop & Progressbar are inconsistent
    • drag and drop adds functionality to a selector
    • progress injects an element into the selector
Copy link

yoshuawuyts commented Nov 21, 2016

  1. Do you think we should separate logic components/plugins from views? Now
    they are coupled together — when you update state (logic), re-render is
    called on all plugins. If we do that, we can in theory re-use logic in all
    environments that support JS, while suppling separate React/React
    Native/JSX/Bel/Angular/Whatever UI component.

Yeah I think that sounds good - from what you're saying that leads to a less
coupled architecture which is a good thing.

In the example you posted, the contents of the returned el can be updated by
uppy without any trouble, causing the DOM to be updated in return. You're
right in that it does complicate the views a little, but I feel that's the
nature of how unidirectional updates work; if you provide default props the
user can mount into their global state things become easier tho.

How would this work if plugins can only modify state, should they set a flag
like newState = {beginUpload: true}?

Yup, I feel using proper delimited names this would work well; in essence it's
the same idea as a central event bus, but using a different (more convenient)

But we might want to mount to multiple places

I think that mounting in several places means you've got different elements
that need to be mounted. If that's the case then those elements are most likely
generated by different plugins, which could each return their own DOM element.

so .use() would detect the .plugin value on any given value passed in and use
that as a plugin

Don’t get that part. In your proposed example plugins look
like this: function (state, cb) {}. Where would the .plugin go? Or do you
mean we keep current structure where plugins are objects that have methods
and properties?

const uppy = require('uppy')
const html = require('bel')

const el = myCoolPlugin()

const upload = uppy()
upload.use(el) // reads out the .plugin value, yay!


function myCoolPlugin () {
  const el = html`<main>DOM element goes here</main>`
  el.plugin = function (my, params) {
    // this is a property on our dom element that can be picked up by uppy.
    // This makes it so it can both be rendered on the DOM as passe directly
    // into Uppy
  return el

  1. Yup, agree to all you said there

Where do I debounce this: in uploader plugin that updates state with
progress, or in view that displays progress?

Good question. I don't have an answer from experience there, but instinctively
I'd say both.

  1. In Choo you use Request Animation Frame. Should we do that too? What if we
    just wrap yo.update() in a window.requestAnimationFrame()? Not sure I
    understand why raf and nanoraf modules exist (I did look inside, but still
    confused), node support?

nanoraf exists to make it so re-renders don't happen if new state wasn't
flushed down. Actually refreshing at 60fps causes most CPUs to spin so you
don't wanna do that; instead only re-render when new stuff happens, capped at
60fps is like a good way of doing things. That's what nanoraf does for you. the
raf package is a polyfill for browsers that don't support it.

We might feel like yo-yo is not working for us

Yeah, yo-yo is a low-level library - it might not be for everyone. I'm not sure
what I'd recommend for building libraries if not yo-yo; using JSX won't
necessarily help with things like this. Have you taken a look at
cache-element at all? - It's a bit young still, but I think it should help
squash some of the duplicate fetch issues at least.

I hope this provides a sufficient answer to your questions!

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment