Get MPC signature pieces from a transaction hash, like one returned from MyNEARWallet as a URL param

get-mpc-signature-from-tx-hash.js

// run with "node get-mpc-signature-from-tx-hash.js" or whatever name

const { connect, keyStores } = require('near-api-js')

const mockKeyStore = new keyStores.InMemoryKeyStore()
const nearConfig = {
    keyStore: mockKeyStore,
    networkId: 'testnet',
    nodeUrl: 'https://archival-rpc.testnet.near.org',
}

const start = async () => {
    const near = await connect(nearConfig)
    const jsonProvider = near.connection.provider

    const txResult = await jsonProvider.txStatus('AaqDJeiXcwRgE1FxoZqjRXUrdodWYSvh7rAiTQVoUGEZ', 'mike.testnet')

    console.log('txResult.status', txResult.status)
    console.log('\nNote: the previous log shows the "status" key. More details are available.')

    if (Object.keys(txResult.status).length === 1 && 'SuccessValue' in txResult.status) {
        const successValue = txResult.status.SuccessValue
        const decodedValue = Buffer.from(successValue, 'base64').toString('utf-8')
        console.log('Decoded SuccessValue:\n')
        // If this transaction hash points to an MPC signature response,
        // it will be an array of two elements that need to be joined, like here:
        // https://github.com/Pessina/near-sandbox/blob/0680809ef19b66be184adb74f7d2f3fdc38ae8e0/utils/chain/Bitcoin.tsx#L247-L272
        console.log(decodedValue)
    } else {
        console.log('SuccessValue is either missing or there are other keys present.')
    }
}

// Calls start function
(() => start())()