Cycle model draft (not working) for more complex objects

mediaAsset-model-draft.js

// This doesn't work, it's just a draft while thinking how best to model collections of non-trivial objects
const model = (function () {
  const mediaAsset$ = createStream(droppedFiles$.filter(droppedFile => droppedFile.type.match('image.*'))
    .map (droppedfile => {
      const reader = new FileReader();

      const asset = {
        id = cuid(),
        name = droppedfile.name,
        imageLoadSucceeded$ = Rx.Observable.fromEvent(reader.onload).map(_ => reader.result),
        imageLoadFailed$ = Rx.Observable.fromEvent(reader.onerror).map(_ => false),
        imageLoadProgress$ = Rx.Observable.fromEvent(reader.onprogress).map(eventData =>
          eventData.lengthComputable ? (eventData.loaded / eventData.total) : 0)
      };

      reader.readAsDataURL(droppedfile);
      return asset;
    }));
  const collectedMediaAssets = mediaAsset$.scan(new Map(), (itemMap, item) => itemMap.set(item.id, item));
  return {
    mediaAsset$,
    collectedMediaAssets,
    inject(intent) {
      mediaAsset$.inject(intent.droppedFiles$);
      return intent;
    }
  }
})();