Deploying to L2 networks in Blockchain / Solidity - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to specify the Layer 2 network RPC URL.

Blockchain / Solidity

const provider = new ethers.providers.JsonRpcProvider('[1]');

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Ahttps://polygon-mumbai.infura.io/v3/YOUR-PROJECT-ID

Bhttps://rinkeby.infura.io/v3/YOUR-PROJECT-ID

Chttps://localhost:8545

Dhttps://mainnet.infura.io/v3/YOUR-PROJECT-ID

Attempts:

3 left

💡 Hint

Common Mistakes

Using a mainnet RPC URL instead of an L2 testnet URL.

Using a local blockchain URL which is not an L2 network.

The Polygon Mumbai testnet is a popular L2 network for deployment, so its RPC URL is used here.

2fill in blank

medium

Complete the code to deploy a contract using the signer connected to the L2 network.

Blockchain / Solidity

const signer = new ethers.Wallet('0xYOUR_PRIVATE_KEY', provider);
const factory = new ethers.ContractFactory(abi, bytecode, [1]);
const contract = await factory.deploy();

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Asigner

Bprovider

Cwallet

Dcontract

Attempts:

3 left

💡 Hint

Common Mistakes

Passing the provider instead of the signer.

Passing an undefined wallet object.

The ContractFactory needs a signer to deploy the contract, so we pass the signer object.

3fill in blank

hard

Fix the error in the code to wait for the contract deployment transaction to be mined on the L2 network.

Blockchain / Solidity

const tx = contract.deployTransaction;
await tx.[1]();

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Aconfirm

Bwait

Cmine

Dsend

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'send' which sends a transaction but does not wait.

Using 'mine' or 'confirm' which are not valid methods.

The correct method to wait for a transaction to be mined is wait().

4fill in blank

hard

Fill the blanks to create an object that maps contract names to their deployed addresses on the L2 network, filtering only those with addresses starting with '0x'.

Blockchain / Solidity

const deployedContracts = Object.keys(contracts).reduce((acc, [1]) => {
  if (contracts[[1]].address && contracts[[1]].address.[2]('0x')) {
    acc[[1]] = contracts[[1]].address;
  }
  return acc;
}, {});

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Aname

BstartsWith

Cincludes

Daddress

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'includes' instead of 'startsWith' which checks anywhere in the string.

Using 'address' as the loop variable which is incorrect.

We use 'name' as the variable for keys and 'startsWith' to check the address prefix.

5fill in blank

hard

Fill all three blanks to filter and map contract deployment info: create a new object with keys as uppercased contract names, values as addresses, only for contracts deployed on the L2 network with gas used greater than 100000.

Blockchain / Solidity

const filteredContracts = Object.entries(deployments).reduce((acc, [constName, info]) => {
  if (info.network === 'L2' && info.gasUsed [3] 100000) {
    acc[[1]] = [2];
  }
  return acc;
}, {});

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AconstName.toUpperCase()

Binfo.address

C>

DconstName

Attempts:

3 left

💡 Hint

Common Mistakes

Using the original contract name instead of uppercased.

Using '<' instead of '>' for gasUsed comparison.

We uppercase the contract name for the key, use the address as value, and filter gasUsed greater than 100000.