Questions tagged [web3js]
Javascript API and library for Ethereum To develop applications on Ethereum, you can use the web3 object provided by the web3.js library. Under the hood it communicates to a local node through RPC calls. web3.js works with any Ethereum node, which exposes an RPC layer. https://github.com/ethereum/wiki/wiki/JavaScript-API
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questions with no upvoted or accepted answers
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getting started with geth and ENS commands: Error: invalid address
I'm starting from square zero, sorry. I'm just trying to get a javascript console up and running so that I can learn more about ENS:
http://docs.ens.domains/en/latest/userguide.html#resolving
I've ...
6
votes
0
answers
843
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How to Catch Connection Issues to Web3 Provider using Web3.js
My node.js script is able to successfully connect to the Web3 provider when both the private key (using truffle-privatekey-provider) and the provider host URL are correct.
let privateKey = ...,
...
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6
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Use of web3.js batch requests
The web3.js API allows for synchronous RPC batch requests
with the example given as:
var batch = web3.createBatch();
batch.add(web3.eth.getBalance.request(
'...
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6
votes
1
answer
841
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Problem with start() in web3-provider-engine
While trying to connect to a provider(infura) I get the above error below is the full stack trace:
bundle.js:54318 Uncaught TypeError: this.provider.sendAsync is not a function
at Web3Subprovider....
5
votes
1
answer
283
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Does anything change on getGasPrice( ) in Web3js after EIP-1559?
Using getGasPrice in web3js returns the last few blocks median gas price. After EIP-1559, the fees system is divided into Base + Tip.
My question is, what is returned using getGasPrice after EIP1559? ...
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Can gas price and amount of gas be automatically set by metamask, or are they required to be set via code in web3.js (EIP-1559)?
I am using web3.eth.Contract to deploy a smart contract to the ropsten testnet. To interact with metamask I am using window.ethereum. I deploy the contract via the code below that I found on https://...
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5
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2
answers
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sign transaction in web3 with metamask
I'm trying to make a signed transaction in browser with web3 injected from metamask and send the transaction to my backend-server and then submit it to blockchain.
However, it's hard to find how I can ...
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5
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Why does Ethereum use JSON-RPC and not gRPC?
I am fairly new to networking protocols especially JSON-RPC and gRPC as they are not nearly as common in web development as REST. I was reading around and seems like gRPC generally performs better. So ...
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5
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937
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Unit testing a Solidity Library function with a struct memory argument
I am trying to unit test a Solidity Library contract function using truffle and web3. My simplified Library contract looks like this:
pragma solidity >=0.5.16;
pragma experimental ABIEncoderV2;
...
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5
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0
answers
506
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Truffle test of two transactions during the same block
I'm trying to test a solidity function that only allows it to be called once per block. E.g. (my desired functionality):
Tx1 calls Fn during block #100, and when successful sets a boolean flag for ...
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5
votes
1
answer
712
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Can't debug transactions that fail during the Web3.js estimateGas() call? No Tx Hash
NOTE: I am doing my work with the Ganache v1.2.2 GUI client on a Linux Ubuntu 18.04 station.
There are many revert errors that happen during the estimateGas() call that precedes the actual Web3.js ...
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5
votes
1
answer
952
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web3.eth.getBlock returns null
I have a very similar problem as https://github.com/paritytech/parity-ethereum/issues/8788
When I use web3.eth.getBlock for the first 1 million and latest 50,000 blocks (approximately), I get the ...
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5
votes
1
answer
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Call write function, which doesn't change contract value
I'm new in smart contracts and faced with one problem.
After deploying contract to my test local blockchain network, i try to set new value via setter, after that I call get method of contract and it ...
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5
votes
2
answers
615
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How to access dynamic list from web3?
In my application players can create and join games. I store every game in a mapping(uint => Game), and send out a GameCreated event whenever a game is created. My issue is efficiently getting a list ...
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5
votes
1
answer
259
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web3.eth.compile.solidity(source) throws me Invalid JSON RPC response
I am relatively new to Blockchains and when I execute the following command I am getting an error.
contract mortal {
address owner;
function mortal() {
owner = msg.sender;
}
...
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4
votes
0
answers
455
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How to continuesly fork mainnet on latest block
How do I keep the fork mainnet use the latest block using web3?
I need to fork mainnet to latest block before I send the transaction
What originally i do is just run the ganache fork command which ...
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4
votes
0
answers
680
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How to mimic abi.encodeWithSignature in web3?
I have the following function that I would like to test.
function createPlanet(bytes memory _data) public returns (address) {
emit ProxyCreated(planetImplementation);
emit ...
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4
votes
0
answers
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Contract call: data out of bounds
I'm working on a nextjs/react project in which i want to fetch the health factor of an address on AAVE. This can be done by calling getUserAcountData(address) on the lending pool contract. I can ...
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4
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0
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792
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How to get ethereumjs-abi's soliditySHA3 and web3 sign equivalents in ethersjs?
Hello I'd like to create a hash using ethersjs that encodes a number of arguments. I previously used ethereumjs-abi's soliditySHA3 function but not sure which of ethersjs crypto utilities is the ...
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4
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Get RPC URL / IP of Metamask's current provider
Suppose I have multiple copies of the same dapp running on different servers which do not directly communicate with each other, for testing purposes, and can manually interact with different dapp ...
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4
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0
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How to access txpool pending transactions using Netherum?
I want to get list of transactions which are in pending state & queued state in txpool. I can see these transactions in pool using txpool.inspect command.
I tried code given in nethereum sample ...
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4
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Retrieve MetaMask version in web3.js
Is there a way to determine the version of the currently installed MetaMask extension from web3.js?
I can't find it by inspecting the Web3 instance.
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Mining hangs on Generating DAG in progress
I am trying to initialize rpc using the below command and start miner using miner.start(1);
geth --rpcapi eth,web3,personal --rpc --networkid=15
Mining starts successfully with below logs but it ...
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4
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Estimated gas is always low
web3.eth.estimateGas is always calculating low gas for the transaction. Here is a reference to a trasaction in ropsten.
https://ropsten.etherscan.io/tx/...
4
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answers
325
views
Is it possible to see the event log when using eth_call?
I want to perform a transaction locally (with the call method in web3 which perform a eth_call RPC call). It returns only the return value of the function called and I want to see the event log.
I ...
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4
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0
answers
302
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Web3 js events not listening after 5 mins of idle time
My contract is deployed on ropsten infura test-network and that contract has events which gets fired when there is some transaction.
contract file
function functionName(address from, address ...
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4
votes
1
answer
854
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How can I retrieve transaction hashes using web3 batch requests?
When I send a transaction using Truffle's contract wrappers - or using plain web3 sendTransaction() - I get a tx hash back that I can use to confirm the tx has completed. While using batch requests (...
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4
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0
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How to do a disaster recovery in private chains?
How can I do a disaster recovery on a private chain running ethereum, say for instance Quorum ?
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3
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Correctly deploying contracts with web3 1.0 and testrpc (invalid opcode error)
I followed the following tutorial:
https://medium.com/@mvmurthy/full-stack-hello-world-voting-ethereum-dapp-tutorial-part-1-40d2d0d807c2
Now this tutorial is not using the recent version of web3 but ...
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4
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254
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how to get revert at the previous timestamp of evm in testrpc
I am testing my contracts so at some point i need to increase the timestamp of evm that i achieve through evm_timeIncrease but now i want to execute some functions on the basis of current timestamp ...
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4
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2
answers
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Web3 Event Filtering timeout
This is the code I use to get all events from a certain contract.
Solidity:
event NewEvent(address indexed contractAddress, address newBOPAddress, address payer, uint commitThreshold, bool ...
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4
votes
2
answers
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Importing a contract from another contract in NodeJS app
I'm using a function in my NodeJS app to deploy contracts. The user inputs the contract he wishes to deploy and the app deploys it. The structure of the app is
.
├── app
│ ├── models
│ │ └── ...
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4
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Contract execution fails with Web3 but works with Remix
I am dealing with a very simple smart contract:
contract MyRegistry {
struct MyEvent {
string date; // yyyy/mm/dd
string desc; // potentially long string
uint count; // &...
- 181
4
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0
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How to create my own wallet and own blockchain explorer?
I'm running my own private/permissioned ethereum blockchain via geth on Ubuntu. How can i interact with my blockchain to visualize accounts, blocks, transactions etc...?
I've tried a lot of tutorials ...
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3
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How to convert my metamask private key into 32 bytes hexa
How to convert my metamask private key into 32 bytes hexa ?
i am using web3 to start trading on pancake but when i try to convert my bsc metamask phrase keys into hexa is like 150 bytes but require ...
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3
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4
answers
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I keep getting nonce is too low when using truffle to call functions on contracts even though this works fine on remix.How can I fix this
I keep getting the nonce is too low when running functions with sub transactions on the kovan test net is there a way I can stop this from happening?these sub transactions are making transactions with ...
3
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0
answers
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How can I do contract call transaction from Metamask qr code scan?
I have a payable function in the smart contract that takes some ether from the sender and does some tasks. I want to generate QR code for this contract call transaction so that user can scan and ...
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3
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What reason? "Unhandled Rejection (Error): replacement fee too low "
I am going to swap two BSC tokens using etherjs.
I sent approval for a transaction and then I sent a swap transaction.
I am using a Pancakeswap v2 router.
I had this error.
Unhandled Rejection (Error):...
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3
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0
answers
825
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Gas limit too low when using transaction data field
I am using web3.js to send a transaction. This is the code that I have currently:
async function sendTx(tran, ethAddress, privateKey, value=0) {
var tr = {
chainId: await web3.eth....
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3
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0
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How to create a wallet with web3.js
From what I understand, a wallet is a smart contract and in order to create a wallet, you need to deploy the contract to the blockchain as stated here, which is different from creating accounts.
When ...
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How to get a list of all token holders using ethers.js + metamask
Is there any way, using ethers.js and metamask, to build an array of all current token holders? I would need this to my project which I'm currently working at.
I know I can download the entire ...
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3
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2
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How to generate solidity encode function signature from Javascript?
What I am trying to achieve is like , i should be able to call a set of solidity functions dynamically based on some criteria. i'm using call() method to achieve the same.
(bool success, bytes memory ...
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3
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geth javascript console: web3.eth.subscribe ==> "Object has no member 'subscribe'"
I must be missing something -- I am trying to use the web3.eth.subscribe() function in my geth node's javascript console and there is no subscribe function.
Welcome to the Geth JavaScript console!
...
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3
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Swap tokens to Ether on Uniswap V2 TRANSFER_FROM_FAILED
I am trying to swap DAI to ETH on kovan testnet my wallet and contract both have DAI tokens. Whenever I swap the token through web3 the transaction fails Fail with error 'TransferHelper: ...
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3
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1
answer
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how can i translate the ethers.js "getSigner" utility to web3?
I have a web3 object but I'm working off an example that uses ethersProvider.getSigner(). Is there an equivalent (or mostly equivalent) in the web3 library?
For reference, the ethersProvider is ...
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3
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2
answers
133
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Auction contract problem regarding highest bid display
I have an Auction contract which has a function like this:
function bid() payable{
//calculate and store highest bid value
}
But because each transaction takes time to mine, so when a user bids ...
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3
votes
1
answer
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What is the best way to push transactions with hight rate (>1000 per second)?
In order to test the throughput of a private Ethereum, I need to send multiple transactions as fast as possible. Can web3js ensures fast delivery of transactions? or there is an other more efficient ...
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3
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0
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135
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Invalid JSON RPC response on IOS build with Infura
I am developing a mobile DAPP using ionic frame work, everything was fine when I testing on the browser. However I try to build my app on IOS, and run it on my Iphone7, the web3 doesn't work(did't ...
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3
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1
answer
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Most efficient way to get all non-zero storage locations for a smart contract?
I'm looking at a mainnet smart contract and want to figure out all storage positions/slots where the storage has a non-zero value.
Is there a way to do this other than replaying and tracing all ...
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3
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0
answers
479
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using events in private blockchain raises leveldb not found error
i'm getting { [Error: Node error: {"code":-32000,"message":"leveldb: not found"}] when trying to use events on a private eth blockhain.
What might be the problem? (I've installed Leveldb with brew)
...
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