c2e573479c - EDM-937:
added prefetching to Smart Links rendering path.
As of this version of @atlaskit/smart-card, when a Smart Link is initially rendered, one of two
things will take place:
- The link will be considered as within the viewport, and a
fetch and render path will be
taken, or;
- The link will be considered as outside of the viewport, and a
prefetch and render later path
will be taken.
In the latter, the approach taken has been to separate the rendering of the UI of Smart Links from
the data backing the Smart Link. This is important, as, otherwise, the browser will become
extremely busy even though Smart Links are not in the viewport. Thus, instead, the data for Smart
Links is fetched in the background, and persisted to the store.
A few additional points here are:
- The prefetching logic has been implemented as a hook which can be used in other components,
usePrefetch;
- The prefetching logic is error-safe, in that, if errors take place whilst replacing there should
be no repercussions (this has been tested);
- The prefetching logic and fetching logic peacefully co-exist, in that, if a link is scrolled
into view whilst it is being prefetched, subject to prior logic in the Smart Links reducers,
either one or the other is taken as the canonical source of truth for representation of the
link's metadata (whichever finishes first, to benefit the customer experience).
Tests have been added to verify associated functionality, with an integration test added to ensure
the number of network requests at two points, (1) on initial page load and, (2) after scrolling to
the end of the page are the same.
Note: Prefetching is enabled by default. This is deliberate to minimise the UI reflow and
associated 'jank' in the Smart Links experience. If required, opt-out behaviour will be provided
in the future.
