How to decode transaction input data using `ethers.utils.interface

[ethdev279]

I'm fetching transaction data using Etherscan API. This is the example result I'm getting:

{
  blockNumber: '7409930',
  timeStamp: '1639151980',
  hash: '...',
  nonce: '4124',
  ...
  input: '0x9d90e4c8000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000040000000000000000000000000000000000000000000000000000000000000002000000000000000000000000093238bb66b5d15b4152c5db574e3397ff1b1a450',
  contractAddress: '',
  cumulativeGasUsed: '403775',
  gasUsed: '1162315',
  confirmations: '191308'
}

Now I need to figure out the contract method, e.g. TransferOwnership, stakeTokens and input parameters it is taking for this transaction. I'm looking at https://docs.ethers.io/v5/api/utils/abi/interface/#Interface--decoding but couldn't find anything related to this. @ricmoo

This is an exception issue

• I understand this form is for exceptional issues and believe my issue qualifies.

[zemse]

Once you get the abi from etherscan API:

const iface = new ethers.utils.Interface(abi);
const decodedArgs = iface.decodeFunctionData(tx.input.slice(0,10), tx.input)
const functionName = iface.getFunction(tx.input.slice(0,10)).name

[travis-rx]

Error: TypeError: Cannot read properties of undefined (reading 'Interface')

Solution: const iface = new ethers.Interface(abi);

Just remove the utils

[alexisnsns]

@TrasherTravis thank you king you made my day 👑

[JoeyEttinger]

I know you might not see this because this post is so old, but in case you do, I had a quick question. I am able to "decode" the data in the sense that it prints out a bunch of stuff including a "result" array of size four, which I presume contains the function call and parameter that I am actually looking for. However, each item in this array is still encoded. Any idea how to decode it further?