Why it is recommended to emit the event CreatedNFT before we actually mint the NFT with _safeMint()

[sadityakumar9211]

Why is it recommended to fire the event of CreatedNFT before we even mint the NFT using _safeMint function? Am I wrong with this assumption?

[zeroxvee]

We only do so, because afterwards we update the token counter, so we use the current tokenId to emit an event, mint the nft, then update the counter.
In reality it doesn't matter, because _safeMint is making sure we are sending an NFT to a contract that can work with the NFT later. If a contract doesn't implement ERC721 Interface, mintNft will be reverted, because otherwise such a contract won't have an ability to transfer this NFT making it a "lost" NFT.

Original code:

function mintNft(int256 highValue) public {
    s_tokenIdToHighValue[s_tokenCounter] = highValue;
    emit CreatedNFT(s_tokenCounter, highValue);
    _safeMint(msg.sender, s_tokenCounter);
    s_tokenCounter++;

Otherwise, we could just use a temporary variable:

function mintNft(int256 highValue) public {
    uint256 tokenId = s_tokenCounter;
    s_tokenCounter++;
    s_tokenIdToHighValue[tokenId] = highValue;
    _safeMint(msg.sender, tokenId);
    emit CreatedNFT(tokenId, highValue);
    }