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AsyncDataEnvelopes are plain JavaScript objects created in the global state by useAsyncData() and useAsyncCollection() hooks to hold loaded async data and related meta data.


  • data - any - The loaded async data.
  • numRefs - number - The count of currently mounted components referencing the async data via useAsyncData() and useAsyncCollection() hooks.
  • operationId - string - A unique ID of the current data loading operation, if one is in progress. Changing this ID before the operation ends effectively cancels it, and instructs related hooks to ignore the operation result.

    Server-side and client-side operation UIDs start with S and C letters respectively. At the client side, if an envelope stores operationId starting with S letter, it is understood as a non-terminated data loading operation during SSR, and it is automatically restarted at the client-side in such case.

  • timestamp - number - Unix timestamp (in milliseconds) of the most recently loaded data payload.