Subscriptions work similarly to other reactive JS frameworks.
You can subscribe to a query of Replicache and you will get notified when that query changes for any reason — either because of local optimistic changes, or because of sync.
Subscriptions are Fast
Replicache goes to significant trouble to make reactive renders efficient:
- Replicache only calls the query function (the parameter to subscribe) when any of the keys it accessed last time change.
onDatacallback is only called when the result of the query function changes.
- Replicache will usually return objects with the same identity across queries, so you can use things like React’s
useMemoto avoid re-renders.
Modify the sample to increment by zero, and verify that the
onData callback is not called. This is because even though the
count key was re-written, its value didn't change. So Replicache didn't call the