Fungujs

Fungujs is a fictional JavaScript library introduced in instructional material to illustrate how to model and manipulate fungible data within software systems. The name signals interchangeable resources such as currencies, tokens, or countable assets, and the project is presented as a teaching tool rather than a production aid.

Core abstractions include FungibleValue, representing an amount with an optional unit, and Ledger, a mapping from account identifiers to balances. The API exposes arithmetic operations like add, subtract, and compare, with validation to prevent negative balances. Transfers model movement of value between accounts and can be composed with other transformations.

Fungujs emphasizes functional programming practices by favoring pure functions that return new values rather than mutating inputs. State is typically treated as immutable and threaded through a sequence of transformations. Optional plugins provide streaming adapters and auditable event logs.

Typical usage involves creating accounts, executing transfers, and querying balances to verify outcomes. The library highlights error handling and deterministic behavior, making it useful for demonstrations and lightweight simulations.

Architecturally, Fungujs aims for a small core with modular extensions for persistence, auditing, or integration with external data sources. It targets browser and Node environments and is described in tutorials as a minimal, dependency-light package.

As a fictional concept, there is no official repository or production release. It is primarily used for educational examples and to discuss design choices around fungible data handling. Related topics include fungible tokens, ledgers, functional programming, and JavaScript libraries.