Kotlin Data Classes Work as HashMap Keys, but TypeScript Map Lookups Fail on Objects

A Kotlin data class used as a map key matches by value, since the compiler generates equals and hashCode from its properties. Porting the same pattern to TypeScript fails because JavaScript's Map and Set compare object keys by reference rather than by content. Adding an equals method does not help, because JavaScript collections never call it. The author notes that using a plain object as a dictionary is also flawed, since every object's key coerces to the same string. The suggested fix is to derive a primitive string key from the fields, using JSON encoding for strings to avoid ambiguity.