creatingAnInfiniteLoadingList.md

Creating an Infinite-Loading List

The InfiniteLoader component was created to help break large data sets down into chunks that could be just-in-time loaded as they were scrolled into view. It can also be used to create an infinite-loading list (eg. Twitter or Facebook). Here's a basic example of how you might implement that:

function MyComponent ({
  /** Are there more items to load? (This information comes from the most recent API request.) */
  hasNextPage,
  /** Are we currently loading a page of items? (This may be an in-flight flag in your Redux store for example.) */
  isNextPageLoading,
  /** List of items loaded so far */
  list,
  /** Callback function (eg. Redux action-creator) responsible for loading the next page of items */
  loadNextPage
}) {
  // If there are more items to be loaded then add an extra row to hold a loading indicator.
  const rowCount = hasNextPage
    ? list.size + 1
    : list.size

  // Only load 1 page of items at a time.
  // Pass an empty callback to InfiniteLoader in case it asks us to load more than once.
  const loadMoreRows = isNextPageLoading
    ? () => {}
    : loadNextPage

  // Every row is loaded except for our loading indicator row.
  const isRowLoaded = ({ index }) => !hasNextPage || index < list.size

  // Render a list item or a loading indicator.
  const rowRenderer = (index) => {
    if (!isRowLoaded(index)) {
      return 'Loading...'
    } else {
      return list.getIn([index, 'name'])
    }
  }

  return (
    <InfiniteLoader
      isRowLoaded={isRowLoaded}
      loadMoreRows={loadMoreRows}
      rowCount={rowCount}
    >
      {({ onRowsRendered, registerChild }) => (
        <VirtualScroll
          ref={registerChild}
          onRowsRendered={onRowsRendered}
          rowRenderer={rowRenderer}
          {...otherProps}
        />
      )}
    </InfiniteLoader>
  )
}