Category: Ethereum

Should web3.currentProvider.send() return a promiEvent when called with async/await?

Post author By Crypto Questions
Post date March 10, 2021
No Comments on Should web3.currentProvider.send() return a promiEvent when called with async/await?

According to the web3.js docs I’d expect it shouldn’t be necessary to use callbacks. When no callback is passed, promise-like "promiEvents" should be returned. Why is the ouput of the following example "result undefined"? try { const result = await web3.currentProvider.send({ method: "eth_sendPrivateTransaction", params: [ signedTx ], jsonrpc: "2.0", id: new Date().getTime() }); console.log(‘result’, result); […]

Tags "jsonrpc": "2.0", According to the web3.js docs I'd expect it shouldn't be necessary to use callbacks. When no callback is passed, id: new Date().getTime() }); console.log('result', params: [ signedTx ], promise-like "promiEvents" should be returned. Why is the ouput of the following example "result undefined"? try { const result = awai, result); } catch (err) { console.error(err); } It seems like there's an unresolved issue on GitHub related to this. Is it still nece

Cryptocurrency Ethereum Mastering Development

Was Uniswap a DAO even before it had it’s governance token, the UNI?

Post author By Crypto Questions
Post date March 10, 2021
No Comments on Was Uniswap a DAO even before it had it’s governance token, the UNI?

A Decentralised Autonomous Organization is governed by a governance token. So democratically, everybody who owns the token could vote on proposals and submit proposals too for the whole DAO. Uniswap didn’t always had it’s UNI token, how did it work before that? Also, can a DAO really be a DAO without a governance token?

Tags A Decentralised Autonomous Organization is governed by a governance token. So democratically, can a DAO really be a DAO without a governance token?, everybody who owns the token could vote on proposals and submit proposals too for the whole DAO. Uniswap didn't always had it's UNI token, how did it work before that? Also

Cryptocurrency Ethereum Mastering Development

Token contract: emits Transfer event two times with half value each time, what is the purpose?

Post author By Crypto Questions
Post date March 10, 2021
No Comments on Token contract: emits Transfer event two times with half value each time, what is the purpose?

I stumbled across one contract which emits Transfer event two times: https://etherscan.io/address/0x9dacdbaacff26b233bc6f969f57c61aa0742d4df#code function batchSend(address[] memory _tos, uint _value) public payable returns (bool) { require (msg.sender == owner); uint total = _value * _tos.length; require(balanceOf[msg.sender] >= total); balanceOf[msg.sender] -= total; for (uint i = 0; i < _tos.length; i++) { address _to = _tos[i]; balanceOf[_to] += […]

Tags _to, _value/2); } return true; } Does somebody have any ideas what is the purpose to call the Transfer event two times with half a value, _value/2); emit Transfer(msg.sender, I stumbled across one contract which emits Transfer event two times: https://etherscan.io/address/0x9dacdbaacff26b233bc6f969f57c61aa0742d4df, uint _value) public payable returns (bool) { require (msg.sender == owner); uint total = _value * _tos.length; require(balanceOf[

Cryptocurrency Ethereum Mastering Development

web3 loading issues

i am working on expense tracker dapp using redux/toolkit, when i call the addTransaction function, unfortunately transaction is not getting fulfilled but in console it throews error message ‘TypeError: Cannot read property ‘methods’ of null’, here is full explanation Slice.js import { createAsyncThunk, createSlice } from ‘@reduxjs/toolkit’ import Web3 from ‘web3’ import { EXPENSE_TRACKER_ABI, EXPENSE_TRACKER_ADDRESS […]

Tags 'errors'], "/accounts", []) if someone knows how to solve this, [pushTransactionAsync.fulfilled]: (state, [pushTransactionAsync.pending]: (state, [pushTransactionAsync.rejected]: (state, { useEffect } from 'react'; import { useDispatch, }, accounts and transactions are loaded, accounts: accounts, accounts: null, accounts) let transactionCount = await contract.methods.transactionCount().call(); console.log('transactionCount: ', action) //add web3 for async state.transactions.push(action.payload); state.transactionStatus = 'succeede, action) => { state.errors.push(action.payload); }, action) => { state.errors=[]; } }, action) =>{ console.log('in fulfill transaction state:', action) =>{ console.log('In Pending transaction:', action) =>{ console.log('Rejected'); console.log('in transaction rejected state:', action) =>{ console.log("In fullfil = ", action) state.transactionStatus = 'failed'; state.errors.push(action.error.message); } } }) export const, action); const { web3, action); state.transactionStatus = 'loading'; }, amount, amount: parseInt(amount), async() => { console.log("Web3.givenProvider = ", async(transaction, but except transactions all these three web3, console it console.log('in push transaction state: ', contract, contract == $contract, contract: null, contract) const accounts = await web3.eth.getAccounts() console.log('accounts = ', contracts and accounts are loaded. Store.js import { configureStore, createSlice } from '@reduxjs/toolkit' import Web3 from 'web3' import { EXPENSE_TRACKER_ABI, EXPENSE_TRACKER_ADDRESS } from '../contract/ExpenseTrackerContract'; export const loadWeb3 = createAsyncThunk( 'LoadWeb3', EXPENSE_TRACKER_ADDRESS) console.log("contract = ", extraReducers: { [loadWeb3.fulfilled]: (state, getDefaultMiddleware } from '@reduxjs/toolkit' import { SliceReducer } from './Slice' export const Store = configureStore({ reducer: {, here is full explanation Slice.js import { createAsyncThunk, i am working on expense tracker dapp using redux/toolkit, immutableCheck: false }) }) App.js import React, initialState: { transactions: [], middleware: getDefaultMiddleware({ serializableCheck: false, please help me., receipt) return transaction } ) export const Slice = createSlice({ name: 'ExpenseSlice', reducers: { addError: (state, resetErrors } = Slice.actions export const selectWeb3 = (state) => state.web3; export const selectContract = (state) => state.contract; expor, resetErrors: (state, state) console.log('in fulfill transaction action:', state) console.log('in transaction rejected action:', state); console.log('In Pending transaction action:', state); console.log("In fullfil = ", state); return state.SliceReducer.web3 }) useEffect(()=>{ dispatch(loadWeb3()); // eslint-disable-next-line react-hooks/exha, thunkAPI.getState()) console.log('in push transaction: ', thunkAPI.getState()) it says web3: null contract: null accounts: null transactions: [], thunkAPI) => { console.log('in push transaction state: ', transaction.amount).send({from : accounts[0]}); console.log('receipt: ', transaction) const receipt = await contract.methods.addTransaction(transaction.transactionDescription, transaction) const state = thunkAPI.getState().SliceReducer const contract = state.contract const accounts = state.ac, transactionCount); let transactions = []; for(var i =0; i<transactionCount; i++){ const {amount, transactionDescription, transactionOwner } transactions.push(transaction); //dispatch(addTransaction(transaction)); }, transactionOwner: ', transactionOwner); let transaction = { id: i, transactionOwner} = await contract.methods.transactions(i).call(); console.log('amount, transactions } = action.payload state.web3 = web3; state.contract = contract; state.accounts = accounts;, transactions: transactions} } ) export const pushTransactionAsync = createAsyncThunk( 'PushTransaction', transactionStatus: 'idle', unfortunately transaction is not getting fulfilled but in console it throews error message 'TypeError: Cannot read property 'methods' of null, useSelector } from 'react-redux' import { loadWeb3 } from './store/Slice'; function App() { const dispatch = useDispatch() const web3 =, web3: null, Web3.givenProvider); const web3 = new Web3(Web3.givenProvider); await Web3.givenProvider.enable(); const contract =, when i call the addTransaction function

Cryptocurrency Ethereum Mastering Development

Is the ECDSA signature hash, its derived v value and the chainID still a thing?

Post author By Crypto Questions
Post date March 10, 2021
No Comments on Is the ECDSA signature hash, its derived v value and the chainID still a thing?

I was browsing some code at the go-ethereum and I noticed this method to validate the signature: https://github.com/ethereum/go-ethereum/blob/56dec25ae26bf749b93c3ea69538fabea60c5768/crypto/crypto.go#L263 For convenience this is the comment of the method: ValidateSignatureValues verifies whether the signature values are valid with the given chain rules. The v value is assumed to be either 0 or 1. But in fact the […]

Tags bigIntR, bigIntS, but this is assuming that you generated the signature using crypto.sign which is not relevant for me. So my question is: Is crypto.ValidateS, chainId and it is a lot more involved and the same ecrecover method in go only needs the hash and the signature, I was browsing some code at the go-ethereum and I noticed this method to validate the signature: https://github.com/ethereum/go-ethereum/blob, r, s, splits it in r and s and then it passes them to the method in question like so: isValidWithV0InHomestead := crypto.ValidateSignatureValues(b, the result is always the same with v=0 or v=1 that is: valid if (s < curve.n / 2) If this is correct, then I would only need to ask the HSM for a new signature until crypto.ValidateSignatureValues returns true. ethereum-js seems to have a met, true) //true means homestead as you would expect, true) //true means homestead isValidWithV1InHomestead := crypto.ValidateSignatureValues(byte(1), which were topic that have been discussed here here here and finally here. This is relevant for me as I'm not using crypto.sign instead I'm

Cryptocurrency Ethereum Mastering Development

Is ganache decentralised?

Post author By Crypto Questions
Post date March 10, 2021
No Comments on Is ganache decentralised?

According to Dapp the blockchain should distributed, But while we use ganache it runs on a local machine and the clients will be having only their private key and public key (or wallet) with them AFAIK. Will all the clients using dapp have their own copy of blockchain and i’m asking this since ganache is […]

Tags According to Dapp the blockchain should distributed, But while we use ganache it runs on a local machine and the clients will be having only their private key and public key (or wallet) with the

Cryptocurrency Ethereum Mastering Development

Defi-Staking is it 100% safe?

Post author By Crypto Questions
Post date March 10, 2021
No Comments on Defi-Staking is it 100% safe?

I was reading on crypto staking, more precisely Defi-Staking on Binance: https://www.binance.com/en/defi-staking While I am not a native english speaker I could understand that there is no risk in staking, but what’s the catch? I mean Binance says I can get up to 9% in one single day, but if it’s only about profit then […]

Tags I was reading on crypto staking

Cryptocurrency Ethereum Mastering Development

ethers is not defined

In hardhat, I want to access a contract outside my project in my tests. In my hardhat.config.js I am able to reference external contracts no problem with an ABI and a contract address, like so: const tkn1 = new ethers.Contract(ADDRESS, ABI, signer) However, in my test files, I am getting ethers is not defined when […]

Tags I want to access a contract outside my project in my tests. In my hardhat.config.js I am able to reference external contracts no problem wit, In hardhat

Cryptocurrency Ethereum Mastering Development

Uncaught TypeError: CoursetroContract.at

Post author By Crypto Questions
Post date March 10, 2021
No Comments on Uncaught TypeError: CoursetroContract.at

index1.html:75 Uncaught TypeError: CoursetroContract.at is not a function at index1.html:75var Coursetro = CoursetroContract.at(‘0xf68CaE6a8F1ED357DAaD76562760eBD7c1f89463’);

Tags index1.html:75 Uncaught TypeError: CoursetroContract.at is not a function at index1.html:75var Coursetro = CoursetroContract.at('0xf68CaE6a8

Cryptocurrency Ethereum Mastering Development

What is the safest way to generate an ethereum wallet for cold storage?

Post author By Crypto Questions
Post date March 10, 2021
No Comments on What is the safest way to generate an ethereum wallet for cold storage?

I am currently making a DIY cold storage using a desktop computer. I cannot find any good desktop wallet for ethereum cold storage. Something like electrum for BTC. So, I can only found these 3 ways to generate a new ethereum wallet address. Using geth account This will create a keystore .json file. I need […]

Tags I am currently making a DIY cold storage using a desktop computer. I cannot find any good desktop wallet for ethereum cold storage. Something, I can only found these 3 ways to generate a new ethereum wallet address. Using geth account This will create a keystore .json file. I need