Browse events in Polkadot.js/api

Question

I want to get events list by using polkadot.js/api.

I can see api.query.system.events() in docs.

Docs: https://polkadot.js.org/docs/substrate/storage#eventcount-u32

However, this api lists events for current block only.

Is there any api to get list of events for specific block height? or range of blocks?

Answer 1

For events (or any queries) at a specific point in the chain -

// Get an API decorated at a specific point. This will -
//   - connect
//   - retrieve the metadata
//   - decorate the API based on what is available
//   - make any state queries at that point
const at = await api.at(blockHash);

// any queries now made will be at that point
const events = await at.query.system.events();

Previously (it is now deprecated, but still available, i.e. not removed), you could also do await api.query.syste.events.at(blockHash). Internally this form would also use the api.at(blockHash) detailed above. The api.at form is preferred since it re-decorates the API at that runtime point, while the older form would assume the state endpoints are the same.