We’ve had Map with those semantics since 2014, came out in Chrome a few months before Set.
Record/Tuple objects are immutable primitives with structural equality, not object reference equality. So little relation to AS3 Dictionary/ES6 Map, besides being possible keys for Map/Set.
> Record/Tuple objects are immutable primitives with structural equality
TIL and also god that would be amazing, almost to the point of making JS/TS actually nice if done right (what’s next, pattern matching?). The number one footgun in JS imo is the combination of mutability and reference copying. Immutable or at least easy-to-copy plain old data is fantastic when it is well supported in the language.
> what’s next, pattern matching?
Oh boy do I have news for you... https://tc39.es/proposal-pattern-matching/
:P
[edit: For those who don't know, Dictionary was a type in AS3 that let you use any object reference or string or number as a unique key, with any type of value attached. Garbage collection worked around this so it wasn't a weak reference as long as the dictionary object itself was alive. Think of a Javascript Set except with strongly typed keys of any kind you specified. Errors thrown at compile time. God..I miss that language.]