Window Focus Refetching

From FR #247

Currently, Apollo Client’s pollInterval refetches every n milliseconds, regardless of whether the user is actively using the page or not, which isn’t optimized. Rising libraries such as SWR or React Query support focus refetching, meaning that the client will not poll if the user has switched to a different tab or window, and it will immediately fetch again if the user comes back to the tab. This saves a lot of wasted requests, while maintaining a great UX.

It would be nice to see such feature implemented in Apollo Client as well.

This is how these 2 libraries implement the focus:

~https://github.com/vercel/swr/search?q=isDocumentVisible&unscoped_q=isDocumentVisible~ ~https://github.com/tannerlinsley/react-query/search?q=isDocumentVisible&unscoped_q=isDocumentVisible~

• https://github.com/vercel/swr/search?q=visibilityState
• https://github.com/TanStack/query/blob/f6eeab079d88df811fd827767db1457083e85b01/packages/query-core/src/focusManager.ts#L22

See FR #247 for more details as it contains a lot of good commentary from the community.

[xcv58]

Hi @jpvajda,

I build a proof of concept implementation: https://github.com/xcv58/apollo-client/pull/1/files#diff-ebf1072d16b9775e8cae2d74140e5da612378bf107621ab70c3769b3c4d31ee5

I think this implementation is not optimal since it will add listeners for each query with the refetchOnFocus: true option. We can add the global listeners on QueryManager class once and use its this.queries.forEach to broadcast when the focus state change and let individual QueryInfo handle the events.

Could you please take a look and share your feedback?

[xcv58]

@jpvajda the links are out of date. Below links are their implementations:

https://github.com/vercel/swr/search?q=visibilityState

https://github.com/TanStack/query/blob/f6eeab079d88df811fd827767db1457083e85b01/packages/query-core/src/focusManager.ts#L22