Reading contract state in Blockchain / Solidity - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to read the contract's stored value.

Blockchain / Solidity

const value = await contract.[1]();

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AstoreValue

BreadValue

CfetchValue

DgetValue

Attempts:

3 left

💡 Hint

Common Mistakes

Using a function that writes data instead of reading.

Calling a function that does not exist in the contract.

The function getValue is the correct contract method to read the stored value.

2fill in blank

medium

Complete the code to connect to the contract using ethers.js.

Blockchain / Solidity

const contract = new ethers.Contract(contractAddress, abi, [1]);

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Aprovider

Bsigner

Cwallet

Daccount

Attempts:

3 left

💡 Hint

Common Mistakes

Using a signer when only reading data.

Passing an undefined variable.

To read contract state, a provider is used to connect without signing transactions.

3fill in blank

hard

Fix the error in the code to properly await the contract call.

Blockchain / Solidity

const balance = await contract.[1]();

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AgetBalance

Bawait getBalance

Cawait balance

Dbalance

Attempts:

3 left

💡 Hint

Common Mistakes

Including 'await' inside the method name.

Not using 'await' at all causing a Promise instead of value.

The await keyword should be used outside the function call, not inside the method name.

4fill in blank

hard

Fill both blanks to create a dictionary of token balances greater than zero.

Blockchain / Solidity

const balances = { [1]: [2] for (const token of tokens) if (await contract.balanceOf(token) > 0) };

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Atoken

Bawait contract.balanceOf(token)

Ctoken.balance

Dbalance

Attempts:

3 left

💡 Hint

Common Mistakes

Using a property that does not exist on token.

Not awaiting the balanceOf call.

Use token as the key and the awaited balance as the value in the dictionary comprehension.

5fill in blank

hard

Fill all three blanks to filter and map contract events for transfers above 100 tokens.

Blockchain / Solidity

const largeTransfers = events.filter(e => e.args.[1] > [2]).map(e => e.args.[3]);

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Avalue

B100

Cto

Dfrom

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'from' instead of 'to' in the map.

Comparing with a string instead of a number.

Filter events where value is greater than 100, then map to the to address.