Connecting MetaMask wallet in Blockchain / Solidity - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if MetaMask is installed.

Blockchain / Solidity

if (typeof window.ethereum [1] 'undefined') {
  console.log('MetaMask is installed!');
} else {
  console.log('Please install MetaMask.');
}

Drag options to blanks, or click blank then click option'

A===

B!==

C==

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using == instead of !== causes wrong detection.

Using = instead of comparison operator.

We use !== 'undefined' to check if MetaMask (window.ethereum) exists.

2fill in blank

medium

Complete the code to request account access from MetaMask.

Blockchain / Solidity

const accounts = await window.ethereum.request({ method: '[1]' });

Drag options to blanks, or click blank then click option'

Aeth_requestAccounts

Beth_accounts

Ceth_getBalance

Deth_sendTransaction

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'eth_accounts' only returns accounts if already connected.

Using 'eth_getBalance' is for balance, not accounts.

The method 'eth_requestAccounts' asks MetaMask to connect and provide accounts.

3fill in blank

hard

Fix the error in the code to handle MetaMask connection errors.

Blockchain / Solidity

try {
  const accounts = await window.ethereum.request({ method: 'eth_requestAccounts' });
  console.log('Connected account:', [1]);
} catch (error) {
  console.error('User rejected the request');
}

Drag options to blanks, or click blank then click option'

Aaccount[0]

Baccount

Caccounts

Daccounts[0]

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'account' instead of 'accounts'.

Using 'accounts' directly prints the array, not the first account.

The accounts variable is an array; the first account is accounts[0].

4fill in blank

hard

Fill both blanks to listen for account changes and log the new account.

Blockchain / Solidity

window.ethereum.on('[1]', (accounts) => {
  console.log('Account changed to:', [2]);
});

Drag options to blanks, or click blank then click option'

AaccountsChanged

BchainChanged

Caccounts[0]

Daccounts

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'chainChanged' event instead of 'accountsChanged'.

Logging the whole accounts array instead of the first account.

The event 'accountsChanged' fires when user switches accounts. The new account is accounts[0].

5fill in blank

hard

Fill all three blanks to create a function that connects MetaMask and returns the first account.

Blockchain / Solidity

async function connectMetaMask() {
  if (typeof window.ethereum [1] 'undefined') {
    try {
      const accounts = await window.ethereum.request({ method: '[2]' });
      return [3];
    } catch (error) {
      console.error('Connection failed');
      return null;
    }
  } else {
    console.log('MetaMask not installed');
    return null;
  }
}

Drag options to blanks, or click blank then click option'

A!==

B===

Ceth_requestAccounts

Daccounts[0]

Attempts:

3 left

💡 Hint

Common Mistakes

Using === instead of !== for existence check.

Using wrong method name for request.

Returning the whole accounts array instead of first account.

Check if window.ethereum is not undefined, request accounts with 'eth_requestAccounts', and return the first account.