Sending transactions in Blockchain / Solidity - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to send a transaction using the web3 library.

Blockchain / Solidity

const tx = {
  from: senderAddress,
  to: receiverAddress,
  value: web3.utils.toWei('1', '[1]')
};

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

Aether

Bwei

Cgwei

Dtoken

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'wei' directly without conversion.

Using 'gwei' which is a smaller unit.

Using an invalid unit like 'token'.

The value must be converted to wei from ether using web3.utils.toWei with 'ether' as the unit.

2fill in blank

medium

Complete the code to sign the transaction with the private key.

Blockchain / Solidity

const signedTx = await web3.eth.accounts.signTransaction(tx, [1]);

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AtransactionHash

BreceiverAddress

CsenderAddress

DprivateKey

Attempts:

3 left

💡 Hint

Common Mistakes

Using the sender's address instead of the private key.

Using the receiver's address.

Using the transaction hash which is not available yet.

The transaction must be signed with the sender's private key to authorize it.

3fill in blank

hard

Fix the error in sending the signed transaction.

Blockchain / Solidity

web3.eth.sendSignedTransaction([1].rawTransaction)
  .on('receipt', console.log);

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AsignedTx

Btx

Ctransaction

Dreceipt

Attempts:

3 left

💡 Hint

Common Mistakes

Using the original transaction object instead of the signed one.

Using undefined variables.

Using the receipt object before sending.

The signed transaction object is signedTx, which contains the rawTransaction property.

4fill in blank

hard

Fill both blanks to create a transaction object with gas and gasPrice.

Blockchain / Solidity

const tx = {
  from: senderAddress,
  to: receiverAddress,
  value: web3.utils.toWei('0.5', 'ether'),
  gas: [1],
  gasPrice: web3.utils.toWei('[2]', 'gwei')
};

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A21000

B50

C100000

D10

Attempts:

3 left

💡 Hint

Common Mistakes

Using too low gas limit causing transaction failure.

Using gas price in wei instead of gwei.

Confusing gas and gasPrice values.

The standard gas limit for a simple ETH transfer is 21000, and a common gas price is 50 gwei.

5fill in blank

hard

Fill all three blanks to create a transaction receipt handler.

Blockchain / Solidity

web3.eth.sendSignedTransaction(signedTx.rawTransaction)
  .on('[1]', (receipt) => {
    console.log('Transaction [2] with hash:', receipt.[3]);
  });

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Areceipt

Bconfirmation

CtransactionHash

Derror

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'error' event instead of 'receipt'.

Logging wrong receipt properties.

Confusing event names.

The event to listen for is 'receipt', the message says 'confirmation', and the receipt object has the 'transactionHash' property.