js-on-sx: globalThis self-ref, toFixed range + 1e21 fallback

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.
 
+- 2026-05-10 — **`globalThis.globalThis === globalThis`; `Number.prototype.toFixed` honours digit-range and ≥1e21 fallback.** (1) `globalThis` was bound to `nil` in the global object literal (originally to dodge an inspect-cycle hang) — added `(dict-set! js-global "globalThis" js-global)` after the literal so `globalThis.globalThis === globalThis` per spec. (2) `Number.prototype.toFixed` rewrites: RangeError when fractionDigits is NaN or outside `[0,100]` (was silently producing garbage), and for `|x| >= 1e21` returns `js-number-to-string` (the value's own ToString) per spec step 9. conformance.sh: 148/148.
+
 - 2026-05-10 — **`delete <ident>` returns `false` instead of `true` per non-strict spec.** ES non-strict semantics: `delete x` where `x` is a declared binding (variable / function / parameter) returns `false` and does not unbind. Our transpiler was emitting `true` for any `delete <expr>` whose argument wasn't a member or index access. Now `delete <js-ident>` → `false`, and `delete <js-paren expr>` recurses on the inner expression so `delete (1+2)` still works. Result: language/expressions/delete 14/30 → 18/30 (+4). conformance.sh: 148/148.
 
 - 2026-05-10 — **Parser rejects unary-op directly before `**` (e.g. `-1 ** 2`, `delete o.p ** 2`, `!x ** 2`, `~x ** 2`) per ES spec.** ES disallows `UnaryExpression ** ExponentiationExpression`; only `UpdateExpression ** ExponentiationExpression` and `(<UnaryExpr>) ** ...` are legal. Added a guard in `jp-binary-loop`: when op is `**` and the LHS is a `(js-unop ...)` node, raise SyntaxError. Parens are made transparent for everything except this check via a new `jp-paren-wrap` helper that emits `(js-paren <unop>)` only when wrapping an explicit unary op (so `(-1) ** 2` parses fine), and a new `js-paren` AST tag in `js-transpile` that just unwraps. Result: language/expressions/exponentiation 25/30 → 28/30 (+3). conformance.sh: 148/148.