user81044: I've set up zeromq so I can listen for blocks & transactions. However I'm not certain how I can ping the bitcoin node for older information.
Is there someway I can ping the bitcoin node for say a block at X height or say a transaction with X id?

user-1: getrawtransaction can be used for transactions if txindex=1 is saved in config
getblock can be used for blocks
Since you mentioned nodejs, you should check bcoin: https://github.com/bcoin-org/bcoin
Bitcoin nodes can even be run in browser.

81044: <p>I've set up zeromq so I can listen for blocks &amp; transactions. However I'm not certain how I can ping the bitcoin node for older information.</p>
<p>Is there someway I can ping the bitcoin node for say a block at X height or say a transaction with X id?</p>
 -1: <p><a href="https://bitcoincore.org/en/doc/0.21.0/rpc/rawtransactions/getrawtransaction/" rel="nofollow noreferrer"><code>getrawtransaction</code></a> can be used for transactions if <code>txindex=1</code> is saved in config</p>
<p><a href="https://bitcoincore.org/en/doc/0.21.0/rpc/blockchain/getblock/" rel="nofollow noreferrer"><code>getblock</code></a> can be used for blocks</p>
<p>Since you mentioned nodejs, you should check bcoin: <a href="https://github.com/bcoin-org/bcoin" rel="nofollow noreferrer">https://github.com/bcoin-org/bcoin</a></p>
<p>Bitcoin nodes can even be run in <a href="https://bcoin.io/browser/" rel="nofollow noreferrer">browser</a>.</p>
