[Ethereum] Getting Metamask account’s balance using fromWei

angular2balancestypescriptweb3js

Using web3 javascript code to get selected account's balance in Metamask and show it in html,

web3.eth.getCoinbase(function(err, account) {
  if (err === null) { 
    App.account = account;
    $("#account").text(account);
    web3.eth.getBalance(account, function(err, balance) {
      if (err === null) {
        $("#accountBalance").text(web3.fromWei(balance, "ether") + " ETH");
      }
    });
  }
});

and now I'm using angular 4 trying to convert above code to typescript.

const Web3 = require('web3');
const contract = require('truffle-contract');
const myBettingArtifact = 
require('../../../build/contracts/Test.json');
declare var window: any;
...
account: any;
accounts: any;
web3: any;
balance: number;

this.web3.eth.getAccounts((err, accs) => {      
  if (err != null || accs.length === 0) {
    return;
  }
  this.accounts = accs;
  this.account = this.accounts[0];

  this.web3.eth.getBalance(this.account, function(err, balance) {
    this.balance = this.web3.fromWei(balance, "ether") + " ETH"        
  });
});

However I get an error

Uncaught TypeError: Cannot read property 'fromWei' of undefined

What is the problem here?

Best Answer

Apparently, this is not the same inside the anonymous callback function you're passing to getBalance. Try replacing it with a fat arrow function, that binds the outer this value to the inner scope.

this.web3.eth.getBalance(this.account, (err, balance) => {
  this.balance = this.web3.fromWei(balance, "ether") + " ETH"
});

Related Solutions

[Ethereum] Why don’t these transactions add up to the account’s total balance

There is actually one more transaction you are missing, which can be found on the "internal transactions" tab:

https://etherscan.io/address/0x9a77d0900323b5f2b6cff6138569846406cf7456#internaltx

When you include this transaction, you will see that the books balance again.

Internal transactions are those sent by a contract instead of directly from a Externally Owned Account ("EOA" for short). Because they happen "a little further in" to the series of events triggered by some original action an EOA took, they take just a little more work to be identified, and not all block explorers show them. To reflect this different status (as well as the fact that the internal transactions which will eventually result from a currently unconfirmed transaction can't be reliably predicted), Etherscan shows the transaction on a separate tab. But the balances they transfer are regular ether, just like everything else!

[Ethereum] Cant get address balance using web3js

The issue with your testnet url, https://ropsten.etherscan.io/ is not running eth client.

Find below code to connect ropsten node.

const testnet = 'https://ropsten.infura.io/';
const walletAddress = '0x8690F1feff62008A396B31c2C3f380bD0Ca6d8b8';

const web3 = new Web3(new Web3.providers.HttpProvider(testnet));
var balance = web3.eth.getBalance(walletAddress); //Will give value in.
balance = web3.toDecimal(balance);

I am getting value. Now balance will give as wei. Check web3 api method's for the same.

https://github.com/ethereum/wiki/wiki/JavaScript-API#web3towei

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