web3.js | Ethereum JavaScript API | REST library
kandi X-RAY | web3.js Summary
kandi X-RAY | web3.js Summary
This is the Ethereum JavaScript API which connects to the Generic JSON-RPC spec. You need to run a local or remote Ethereum node to use this library. Please read the documentation for more.
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web3.js Examples and Code Snippets
License : Strong Copyleft (CC BY-SA 4.0)
Copyimport Web3 from 'web3'
import Web3 from 'web3/dist/web3.min.js'
// A Web3Provider wraps a standard Web3 provider, which is
// what MetaMask injects as window.ethereum into each page
const provider = new ethers.providers.Web3Provider(window.ethereum)
// MetaMask requires requesting permission to connecconst Web3 = require("web3");
const web3 = new Web3(providerUrl);
web3.eth.accounts.wallet.add(senderPrivateKey);
const contract = new web3.eth.Contract(abiJson, contractAddress);
const executeRelease = async () => {
await contractconst Web3 = require('web3');
const web3 = new Web3(
new Web3.providers.WebsocketProvider(
'wss://speedy-nodes-nyc.moralis.io//bsc/mainnet/ws'
)
);
web3.eth.subscribe('newBlockHeaders', (err, newBlock) => {
console.const transactionParameters = {
from: accounts[0],
to: tokenContractAddress,
data: getDataFieldValue(tokenRecipientAddress, tokenAmount),
};
await ethereum.request({
method: 'eth_sendTransaction',
params: [transactionPa// the sender private key needs to be added to web3 `accounts.wallet`
// see the blue "note" card in the docs for more details
await web3.eth.sendTransaction({
from: senderAddress,
to: contractAddress,
data: "0xd1700e6c..."
}) const web3 = new Web3(provider);
contract = new web3.eth.Contract(
Contract.abi,
Contract.address
);
import json
import sys
from web3 import Web3
bsc = 'https://bsc-dataseed.binance.org/'
web3 = Web3(Web3.HTTPProvider(bsc))
print(web3.isConnected())
contract = '0x40619dc9F00ea34e51D96b6EC5d8a6aD75457434'
contract = web3.toChecksumAddreimport * as web3 from "@solana/web3.js";
import * as splToken from "@solana/spl-token";
const DEMO_WALLET_SECRET_KEY = new Uint8Array([
...
]);
const SOLANA_MAINNET_USDC_PUBKEY = "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v";
(as// erc20.constants.ts
export const WEB3_HTTP_TOKEN = 'WEB3_HTTP_TOKEN';
export const WEB3_WS_TOKEN = 'WEB3_WS_TOKEN'
// erc20.module.ts
import { DynamicModule, Module, Provider } from '@nestjs/common';
import { WEBCommunity Discussions
Trending Discussions on web3.js
QUESTION
I am new to blockchain app development, I saw a project where ganache accounts are imported into Metamask, then web3.js is used to access and print those accounts and balances on Frontend (user interface).
If web3.js can directly access ganache blockchain accounts and balances, why do we need Metamask in between?
...ANSWER
Answered 2022-Feb-08 at 09:11If web3.js can directly acccess ganache blockchain accounts and balances, why we need metamask in between?
In this case, you don't need MetaMask to sign the transaction, as the node (Ganache) holds your private key.
But in a public environment (testnets and mainnet), the node doesn't hold your private key, so you'd need to sign the transaction using MetaMask (or any other tool that holds the private key).
QUESTION
I'm trying to validate that the input text I get from a user is a valid Solana address.
According to the web3.js documentation, the method .isOnCurve() does that:
https://solana-labs.github.io/solana-web3.js/classes/PublicKey.html#isOnCurve
I've managed to make it work with this code:
...ANSWER
Answered 2022-Feb-21 at 04:02To validate a Solana public key may be a wallet address, you should both use isOnCurve() and the PublicKey constructor like you are doing.
The error thrown makes sense. If the address is not a public key, it should not be able to be instantiated.
Perhaps there could be another function made native to @solana/web3.js that takes care of validating wallet addresses for you in the future.
QUESTION
I am new to the field of blockchain and ethereum. I have been trying to create a simple testing network using truffle and ganache where I created a new workplace in truffle and tried to build a quick react frontend app to connect to the ethereum using Web3.
Everything works fine. I did install the MetaMask and created a new network to the port:7545 and every change that happened to the ganache affected the MetaMask.
This is the code of web3 .
...ANSWER
Answered 2021-Aug-14 at 19:08So I tried the same code using truffle and ganache and it works for me. The only difference is that i am running ganache on port 8545 and connecting metamask with that port in url. I believe that you are providing somewhat incorrect values here const todoList = new web3.eth.Contract(TodoList.abi, ADRESS);
Make Sure that your contract's abi and address is correct. Read details about instantiation of contract object with correct values here
Here is how i am reading the JSON file:
const TodoList = JSON.parse(fs.readFileSync('./build/contracts/TodoList.json', 'utf8'));.
I am simply extracting the abi from it just like your code. For Contract Address part, I get the address manually from the output console after running truffle migrate --reset all.
After this you will get a receipt information in console like this
QUESTION
I am trying to create a simple script to test the event listening functionality of Web3.js CreatedPairs. However, my script runs through the code once and then exits instead of continuing to listen for created pairs and I cannot figure out why.
ANSWER
Answered 2022-Mar-21 at 20:42In this context, Web3.givenProvider is null, so the HTTP provider is used.
To be able to subscribe to events, you need to use a WSS provider.
QUESTION
How does one parse the data in an SPL token account? It contains a binary blob and I'd like to get the token type and number of tokens.
An acceptable language is solana-cli, web3.js, or solana.py. I'm looking for any solution.
...ANSWER
Answered 2022-Mar-15 at 03:45The RPC give a great way to parse the data by default. You can use getParsedAccountInfo in web3.js.
Let's take the token account at 9xqnnfeonbsEGSPgF5Wd7bf9RqXy4KP22bdaGmZbHGwp
QUESTION
I am looking for a way to create an automated test suite with Truffle that can test my smart contract's interactions with Uniswap V2. The Uniswap docs briefly mention testing with Truffle but do not provide any examples. I am looking to test it using a mainnet fork with ganache.
I'm guessing it's a similar process to the accepted answer for this question, but I'm specifically looking for a way to do it using Truffle and web3.js.
As an example, if I were testing the following contract:
...ANSWER
Answered 2022-Feb-12 at 12:48If you use Uniswap platform to swap a token, you are going to have 2 steps. You are going to approve the token, in this step metamask will pop-up and you are going to confirm it. Then Uniswap will do the actual swap, it takes the tokens out of your wallet and does the exchange for you.
This is the swapExactETHForTokens function
QUESTION
this is more of a question than an actual issue
I want to use the contract
https://github.com/ironaddicteddog/anchor-escrow
to exchange tokens.
My plan is as follows, however I'm unsuccessful initializing the contract.
ANSWER
Answered 2022-Mar-07 at 08:56I'll answer my own question here, I figured out that the escrow program is already initialized. The error log says that, it cannot use the same escrow account to re-initialize.
QUESTION
I am working on a web application where a NFT owner can stake their NFT and earn rewards. In my application I need to create a transfer request of the NFT from the users wallet to my applications wallet.
Code Example:
...ANSWER
Answered 2022-Mar-06 at 23:51I think this section is your problem:
QUESTION
I am using @solana/web3.js library and have tested to create new account and get balance. Now I am going to integrate the contract (Raydium Liqudity PoolV4) with web3.
I have googled and can not find good material to learn. Can you help me how to integrate the contract in solana using web3? Thanks.
...ANSWER
Answered 2022-Mar-04 at 04:55If you want to integrate with a smart contract, you have to know the source of the smart contract. The program will give you information on how to create the instructions for your transactions.
Let's look at Raydium. They're closed source program-side, but from their client-side code.
We can see that the dataLayout is:
QUESTION
I am following the pet shop tutorial on Truffle. The first few steps work, i.e., I can compile and migrate the Adoption contract. My software versions are:
Truffle v5.4.33 (core: 5.4.33) Ganache v7.0.1 Solidity v0.5.16 (solc-js) Node v17.6.0 Web3.js v1.5.3
Adoption contract code:
...ANSWER
Answered 2022-Mar-03 at 17:47Your contract requires only pets with IDs between 0 and 5 can be adopted:
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