Skills Flashcards

What distinguishes the ERC-1155 standard from ERC-721?

Answer: ERC-1155 supports both fungible and non-fungible tokens in a single contract

ERC-1155 is a multi-token standard allowing fungible, semi-fungible, and non-fungible tokens within one contract.

Which tool would a developer use to connect a web front-end to the Ethereum blockchain and a user's wallet?

Answer: ethers.js or web3.js

Libraries like ethers.js and web3.js let dApps interact with smart contracts and wallets in the browser.

What is a 'reentrancy' vulnerability in smart contract development?

Answer: An attack where an external call re-enters the contract before state updates complete

Reentrancy occurs when a malicious contract calls back into the original function before its state changes finalize, draining funds.

Which pattern helps prevent reentrancy attacks in Solidity?

Answer: Checks-Effects-Interactions

The checks-effects-interactions pattern updates state before making external calls, mitigating reentrancy.

What does 'gas' represent when deploying or interacting with an NFT contract?

Answer: The unit measuring computational work and its fee on Ethereum

Gas measures computational effort, and users pay a gas fee to execute transactions on Ethereum.

What is 'lazy minting' in NFT development?

Answer: Deferring on-chain minting until the moment of purchase to shift gas costs to the buyer

Lazy minting delays the actual on-chain mint until a buyer purchases, so the creator avoids upfront gas costs.

Which file format is standard for NFT metadata that platforms like OpenSea parse?

Answer: JSON

NFT metadata is conventionally stored as a JSON object containing name, description, image, and attributes.