parent-chain-confirmation-checker

Tutorial: Parent chain confirmation checker

parent-chain-confirmation-checker is a simple demo of Arbitrum's transaction finality checker (used to check if a transaction was already submitted to the parent chain or not).

It calls the precompile NodeInterface to find information about a transaction on the parent chain that includes a batch containing the specified child chain's transaction.

This tutorial has 2 scripts; both will show you whether your transaction has been posted in a batch on the parent chain or not.

• The first script, checkConfirmation, will output the number of block confirmations of the batch-posting transaction on the parent chain.
• The second is findSubmissionTx, which will output the batch-posting transaction hash on the parent chain.

See ./exec.js for inline explanations.

Set environment variables

Set the values shown in .env-sample as environmental variables. To copy it into a .env file:

cp .env-sample .env

You'll still need to edit some variables, i.e., CHAIN_RPC and PARENT_CHAIN_RPC.

Note that you can also set the environment variables in an .env file in the root of the monorepo, which will be available in all tutorials.

Run

Script 1: check if the transaction is already on a batch on the parent chain:

yarn checkConfirmation --txHash {YOUR_TX_HASH}

Script 2: get the transaction hash on the parent chain that includes a batch that contains a given transaction of the child chain:

yarn findSubmissionTx --txHash {YOUR_TX_HASH}