js-on-sx: Map and Set constructors with prototype methods

plans/js-on-sx.md

@@ -158,6 +158,8 @@ Each item: implement → tests → update progress. Mark `[x]` when tests green.
 
 Append-only record of completed iterations. Loop writes one line per iteration: date, what was done, test count delta.
 
+- 2026-05-08 — **`Map` and `Set` constructors with full instance API.** Both were undefined globally — every test in those categories died at `new Map()` / `new Set()` with ReferenceError. Implemented as plain SX storage on the instance dict (`__map_keys__` + `__map_vals__` parallel lists for Map, `__set_items__` for Set) using SX `=` for key/value comparisons. Wired prototype methods: `.get`, `.set`, `.has`, `.delete`, `.clear`, `.forEach`, `.keys`, `.values`, `.entries` for Map; `.add`, `.has`, `.delete`, `.clear`, `.forEach`, `.keys`, `.values`, `.entries` for Set. `.size` is a real own property updated on every mutation (no getters). Constructors use the dict-with-`__callable__` pattern (like `Object`) so `Map.length`, `Map.name`, `Map.prototype` work as regular dict reads. Constructor accepts an iterable of `[k,v]` pairs (Map) or values (Set). Added `Map`/`Set` to `js-global` and to the prototype-chain post-init block. Result: built-ins/Map 1/30 → 18/30 (60%), built-ins/Set 0/30 → 15/30 (50%, rest mostly timeouts on iterator-protocol tests). conformance.sh: 148/148.
+
 - 2026-05-08 — **`decodeURI` / `decodeURIComponent` actually decode (and throw URIError on malformed input); harness `decimalToHexString` helper added.** Both were `(fn (v) (js-to-string v))` — passthrough stubs. Implemented the spec algorithm in pure SX: walk percent-encoded sequences, parse hex pair, classify single-byte vs multi-byte (110xxxxx → 2 bytes / 1110xxxx → 3 / 11110xxx → 4), validate the continuation bytes are 10xxxxxx, build the codepoint, reject UTF-16 surrogates and out-of-range. `decodeURI` keeps reserved bytes (`;/?:@&=+$,#`) as literal `%XX`. Malformed sequences throw `URIError` via existing constructor. Also added `decimalToHexString` / `decimalToPercentHexString` to the harness stub — most decodeURI tests `include` that file but the runner doesn't honour `includes`, so the suite was failing with ReferenceError before reaching any URI logic. Result: built-ins/decodeURI 0/60 → 11/60 (rest mostly per-test timeouts on full-codepoint sweeps), built-ins/decodeURIComponent 0/30 → 10/30, built-ins/encodeURI 13/15 → 22/60 unblocked. conformance.sh: 148/148.
 
 - 2026-05-08 — **Object literals: computed keys `[expr]: val`, insertion-order tracking, integer-key-first ordering for `getOwnPropertyNames`.** Three related issues: (1) parser rejected `{[expr]: val}` with "Unexpected in object: punct"; (2) SX dicts use hash-order so `Object.getOwnPropertyNames` returned keys in non-insertion order; (3) `var list = {...}` shadowed the SX `list` primitive, so any later `new Foo()` (which transpiled to `(js-new-call ... (list ...))`) crashed with "Not callable: <dict>". Fixes: parser `jp-parse-object-entry` now accepts `[<expr>]:` and stores `:computed-key`; `js-transpile-object` emits `js-make-obj` (initializes `__js_order__` list) + `js-obj-set!` (appends key on first set); `js-set-prop` / `js-delete-prop` keep the order list in sync; `js-object-keys` and `js-object-get-own-property-names` filter internal keys (`__js_order__` / `__proto__`) and the latter sorts integer keys first per ES spec via a small bubble-sort. Replaced `(list ...)` emissions for `js-new-call` args and array literals with `(js-args ...)` and `(js-make-list ...)` (closure-captured) — the latter remains mutable. Fixes 0/2 → 2/2 on `language/computed-property-names/basics`, +3 on built-ins/Array (Array.from with mapFn + closures over `var list` no longer crashes), no regressions on Object/Number. conformance.sh: 148/148.