ownedTokensIndex
ownedTokensIndex is a data structure used in the ERC721Enumerable extension of the ERC-721 standard to support on-chain enumeration of tokens owned by an address. It is defined as a mapping from a token's identifier (tokenId) to the index at which that token appears in the owner's array of tokens. This index enables constant-time updates when tokens are added to or removed from an owner's balance and makes enumeration efficient.
In typical implementations, each owner maintains an array of their token IDs called _ownedTokens. When a token
The visibility of ownedTokensIndex is typically private or internal, and it is used in conjunction with _ownedTokens
Related concepts include ERC721Enumerable, _ownedTokens, and the internal update routines that maintain consistent enumeration data across