NFT Frontend Minting and Integration 3

Question 1

When a frontend reads an NFT's tokenURI that starts with 'ipfs://', what must it do to fetch the metadata over HTTP?

Accepted Answer

Resolve it through an IPFS gateway URL

Answer

Browsers can't fetch ipfs:// directly, so the URI is rewritten to a gateway like https://ipfs.io/ipfs/<cid>.

Question 2

An NFT's metadata JSON contains an 'image' field. According to common standards, what should the frontend render it as?

Accepted Answer

A URL pointing to the image asset (often IPFS or HTTP)

Answer

The ERC-721 metadata 'image' field is a URI the frontend loads to display the artwork.

Question 3

Why might a frontend cache fetched NFT metadata rather than re-requesting it on every render?

Accepted Answer

Metadata is typically immutable on IPFS, so caching reduces gateway load and latency

Answer

Pinned IPFS metadata rarely changes, so caching avoids repeated slow gateway requests.

Question 4

What is a robust pattern for handling an NFT image that fails to load from one IPFS gateway?

Accepted Answer

Fall back to an alternative gateway via the onError handler

Answer

Using onError to try a backup gateway makes image display resilient to a single gateway outage.

Question 5

When displaying a collection, why is calling 'balanceOf' then 'tokenOfOwnerByIndex' only possible if the contract implements a certain extension?

Accepted Answer

It requires the ERC-721Enumerable extension

Answer

tokenOfOwnerByIndex is part of ERC-721Enumerable, which not all NFT contracts implement.

NFT Development Practice Test