Does a TX hash get produced *before* it's been confirmed in 1 block?

Question

I has code which sends ETH and ERC-20 and of which I want to make sense:

let tx1 = await transferETH(amount, privateKey);
console.log(`${tx1.hash}`);
const receipt1 = await tx1.wait();
console.log(`Done`);

And

let tx2 = await transferERC20(amount, privateKey);
console.log(`${tx2.hash}`);
const receipt2 = await tx2.wait();
console.log(`Done`);

I wonder, is it actually possible for a TX to produce hash before it's been mined into a block?

And which procedure takes at least 10 minutes, as per design of Ethereum protocol:

a) transfer and producing a hash - transferETH/ERC20? Or b) mining a TX into a block - wait()?

Or perhaps a) and b) are more or less close in terms of time they take? One goes immediately, in seconds, after the other, that is.

Answer 1

I wonder, is it actually possible for a TX to produce hash before it's been mined into a block?

The short answer is yes.

The slightly longer answer is, the transaction hash is a fingerprint of the RLP encoded transaction data. For example, here's a link to the go-ethereum repository showing the components of the legacy transaction type: https://github.com/ethereum/go-ethereum/blob/master/core/types/tx_legacy.go#L26-L34. After a transaction is signed the transaction data is serialized using RLP and then submitted to the network (typically via an RPC call like eth_sendRawTransaction).

So yes, one could create and sign a transaction and determine the hash of it prior to even submitting the transaction to the network.

And which procedure takes at least 10 minutes, as per design of Ethereum protocol:
a) transfer and producing a hash - transferETH/ERC20? Or b) mining a TX into a block - wait()?

Since the transition to POS, a new block is produced every 12 seconds. So your 10 minute wait time is due to the priority your transaction is given in the mempool. Your transaction will be mined faster if you were to increase your maxPriorityFeePerGas (or gasPrice if still using the legacy transaction type).