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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Adding Wallet using web3.eth.accounts.wallet.add

On web3 0.20.1, I am using Infura to deploy a contract to Rinkeby. This probably requires me to add a wallet to web3.accounts to provide the gas needed. When I ran the following nodejs code, Web3 = ...
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1answer
438 views

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 ...
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2answers
715 views

How to exchange ETH to DAI with web3 and node.js

I looking for solution how to convert eth to dai with web3 api. something like https://kyber.network/swap/eth_knc (I can send eth to specyfic contract adress and I receive back DAI to the same ...
6
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1answer
733 views

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....
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1answer
858 views

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 ...
5
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2answers
404 views

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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0answers
3k views

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( '...
5
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1answer
236 views

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; } ...
4
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1answer
266 views

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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0answers
359 views

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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0answers
497 views

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 ...
4
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1answer
231 views

DEVp2p Wire Protocol tutorial on geth or Web3.js/Web3.py

I was looking to develop an application using ÐΞVp2p Wire Protocol and I'm having trouble finding an example or tutorial. I was able to find only ÐΞVp2p Wire Protocol's wiki. [Q] Does anybody has a ...
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564 views

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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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 ?
4
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3answers
2k views

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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0answers
227 views

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 ...
4
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2answers
641 views

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 ...
4
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2answers
752 views

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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320 views

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; // &...
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0answers
393 views

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 ...
3
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0answers
74 views

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; ...
3
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2answers
69 views

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 ...
3
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1answer
58 views

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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0answers
1k views

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 ...
3
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0answers
95 views

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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0answers
307 views

Why can't I fetch my Metamask account address with Next.js's getInitialProps?

I'm using Next.js to implement server-side rendering in my Ethereum app, however I can't fetch my Metamask address to display it in the top-right corner of the navigation bar in my index.js file. ...
3
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0answers
225 views

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 ...
3
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0answers
223 views

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 ...
3
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1answer
165 views

Web3JS incorrect return value

When I return a string array with web3 I don't get the original array as expected, but rather I get an array of the same size, with the index off by one. So instead of ["One","Two","Three"] I get ["",...
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0answers
131 views

Quorum :- metamask do not support privateFor feature of quorum

i got to know that metamask do not support privateFor because of which private transaction for quorum dapp was not behaving as expected. so, I can't use metamask for my quorum DApp to switch port and ...
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0answers
886 views

NetworkError when attempting to fetch resource. Resource URL: moz-extension://2…/contentscript.js Source Map URL: ../sourcemaps/contentscript.js.map

I get the following error message in Firefox Developer Tools Console following a successful sendTransaction: "Source map error: TypeError: NetworkError when attempting to fetch resource. ...
3
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1answer
254 views

Create Accounts Using Web3.js in Browser

TL;DR - Replicated Ethereum Blockchain. Running Local Node. Connecting Local Node to Web3.js in browser using RPC. Want to create addresses & send transactions Details - I have a blockchain that ...
3
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1answer
388 views

Retrieve event args from getPastLogs

When we use web3.eth.getPastLogs it returns topic and data properties together with rest data. Does it possible to retrieve event args parsing just data and topic as filter? Without to make additional ...
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0answers
92 views

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.
3
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2answers
372 views

How can we compile multiple smart contracts by compile.js file?

My compile.js file is below const path = require('path'); const fs = require('fs'); const solc = require('solc'); const ballotPath = path.resolve(__dirname, 'contracts', 'blocktitans_ballot.sol'); ...
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0answers
2k views

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 ...
3
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1answer
827 views

Recover address from signature using web3j

I have signed a data string using the following code snippet in web3js var data = "hello world"; web3.personal.sign(web3.fromUtf8(data), web3.eth.accounts[0], function(error, result) { if (!...
3
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0answers
269 views

Error:new bignumber() not a base 16 number

I have built a private chain with two node on two computer. The smart contract was successfully deployed on node1,and i can call the method on node1 ,but when i call the same method on node2,it occur ...
3
votes
1answer
811 views

ERC223 Token Fallback Function Usage

I'm currently writing the "Trade" smart contract which is similar to "Crowdsale" smart contract. The only function that I want to add is "sell" function. In general Crowdsale smart contract is used ...
3
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2answers
771 views

Ropsten infura test network + web3 js event listener

I have deployed contracts on ropsten test network. truffle.js ropsten: { provider: function() { return new HDWalletProvider(mnemonic, "https://ropsten.infura.io/<api-token>") }, ...
3
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2answers
1k views

Invalid address error

I keep getting Error: Invalid address when trying to run the application. My current setup of web3 using infura node is if (typeof web3 !== 'undefined') { web3 = new Web3(web3.currentProvider); } ...
3
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2answers
21k views

TypeError: Cannot read property 'then' of undefined

I am having an error with Web3. After going through all possibilities I decided to post a question hoping for someone with a solution. The error I keep getting is: TypeError: Cannot read property '...
3
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1answer
2k views

Cannot use 'new' with an expression whose type lacks a call or construct signature

A issue in the this.web3 = new Web3(window.web3.currentProvider);the web3.js has output and I type to the code of console.log(window.web3.currentProvider)that window.web3.currentProvider is defined. ...
3
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0answers
894 views

contract.method.getData getData is undefined

When I use contract.method.getData(params) it throws an error getData is undefined. I searched on github and saw someone used request instead, and I used contract.method.request and it has successed! ...
3
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0answers
2k views

How to send transaction with web3.eth.sendTransaction?

I am sending ether by using web3.eth.sendTransaction. But when I send, there is error: Failed to check for transaction receipt: web3.eth.sendTransaction({ from: base_address, to: withdrawer, ...
3
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0answers
193 views

Geth - Events not working/firing

I have an API (expressjs - nodejs) listening for different events from my contract. var web3 = new Web3(new Web3.providers.WebsocketProvider("ws://localhost:8546")); var tokenContract = new web3.eth....
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0answers
85 views

SQL syntax error near `logsBloom` when call web3.eth.sendTransaction

When I am trying to call web3.eth.sendTransaction I receive this error stack: Error: ER_PARSE_ERROR: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server ...
3
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2answers
257 views

Issue with autonomous contract calling erc20 token's transferFrom for approved amount

Trying to transfer fund using ERC20 token handle and calling 'transferFrom'. Assume that the specific amount is preapproved by owner account for 'MyContract' contract address. contract StandardToken {...
3
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0answers
562 views

web3.eth.getBalance(address) throws an error: Invalid JSON RPC response: “”

var web3 = new Web3(new Web3.providers.HttpProvider("http://localhost:8545")); web3.eth.getBalance(address) throws an error: Invalid JSON RPC response: "" while address is some existing valid ...
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0answers
46 views

What are the requirements for contributing a pull request to the Ethereum web3.js repository?

I would like to make a pull request to the web3.js repository (https://github.com/ethereum/web3.js). Are there any requirements, guidelines, etc. I haven't been able to find any information regarding ...

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