js-on-sx: Array.prototype methods carry spec lengths + names

lib/js/runtime.sx

@@ -4369,17 +4369,56 @@
 
 (define js-array-of (fn (&rest args) args))
 
+(define
+  js-array-proto-fn-length
+  (fn
+    (name)
+    (cond
+      ((= name "concat") 1)
+      ((= name "copyWithin") 2)
+      ((= name "every") 1)
+      ((= name "fill") 1)
+      ((= name "filter") 1)
+      ((= name "find") 1)
+      ((= name "findIndex") 1)
+      ((= name "findLast") 1)
+      ((= name "findLastIndex") 1)
+      ((= name "flat") 0)
+      ((= name "flatMap") 1)
+      ((= name "forEach") 1)
+      ((= name "includes") 1)
+      ((= name "indexOf") 1)
+      ((= name "join") 1)
+      ((= name "lastIndexOf") 1)
+      ((= name "map") 1)
+      ((= name "push") 1)
+      ((= name "reduce") 1)
+      ((= name "reduceRight") 1)
+      ((= name "slice") 2)
+      ((= name "some") 1)
+      ((= name "sort") 1)
+      ((= name "splice") 2)
+      ((= name "unshift") 1)
+      ((= name "at") 1)
+      ((= name "toSorted") 1)
+      ((= name "toReversed") 0)
+      ((= name "with") 2)
+      (else 0))))
+
 (define
   js-array-proto-fn
   (fn
     (name)
-    (fn
-      (&rest args)
-      (let
-        ((this-val (js-this)))
+    {:__callable__
+      (fn
+        (&rest args)
         (let
-          ((recv (cond ((list? this-val) this-val) ((and (dict? this-val) (contains? (keys this-val) "length")) (js-arraylike-to-list this-val)) (else this-val))))
-          (js-invoke-method recv name args))))))
+          ((this-val (js-this)))
+          (let
+            ((recv (cond ((list? this-val) this-val) ((and (dict? this-val) (contains? (keys this-val) "length")) (js-arraylike-to-list this-val)) (else this-val))))
+            (js-invoke-method recv name args))))
+      :length (js-array-proto-fn-length name)
+      :name name}))
 
 (define
   js-array-from