downloadUtil.js

const getDownloadItems = (state) => {
  if (!state || !state.get('downloads')) {
    return Immutable.List()
  }

  const downloadsSize = state.get('downloads').size
  const downloadItemWidth = domUtil.getStyleConstants('download-item-width')
  const downloadItemMargin = domUtil.getStyleConstants('download-item-margin')
  const downloadBarPadding = domUtil.getStyleConstants('download-bar-padding')
  const downloadBarButtons = domUtil.getStyleConstants('download-bar-buttons')
  const numItems = Math.floor(
    (window.innerWidth - (downloadBarPadding * 2) - downloadBarButtons) /
    (downloadItemWidth + downloadItemMargin)
  )

  return state.get('downloads')
    .sort((x, y) => x.get('startTime') - y.get('startTime'))
    .skip(downloadsSize - numItems)
    .reverse()
    .map((download, downloadId) => downloadId)
}