diff --git a/lib/js/runtime.sx b/lib/js/runtime.sx
index 2a79d6aa..5ae3611c 100644
--- a/lib/js/runtime.sx
+++ b/lib/js/runtime.sx
@@ -1169,7 +1169,14 @@
       ((= v false) "false")
       ((= (type-of v) "string") v)
       ((= (type-of v) "number") (js-number-to-string v))
-      (else (if (= (type-of v) "dict") "[object Object]" (str v))))))
+      (else
+        (if
+          (= (type-of v) "dict")
+          (if
+            (contains? (keys v) "__js_string_value__")
+            (get v "__js_string_value__")
+            "[object Object]")
+          (str v))))))
 
 (define
   js-template-concat
@@ -1187,6 +1194,32 @@
         (+ i 1)
         (str acc (js-to-string (nth parts i)))))))
 
+(define
+  js-expand-sci-notation
+  (fn
+    (mant exp-n)
+    (let
+      ((di (js-string-index-of mant "." 0)))
+      (let
+        ((int-part (if (< di 0) mant (js-string-slice mant 0 di)))
+          (frac-part
+            (if (< di 0) "" (js-string-slice mant (+ di 1) (len mant)))))
+        (let
+          ((all-digits (str int-part frac-part))
+            (frac-len (if (< di 0) 0 (- (- (len mant) di) 1))))
+          (if
+            (>= exp-n 0)
+            (if
+              (>= exp-n frac-len)
+              (str all-digits (js-string-repeat "0" (- exp-n frac-len)))
+              (let
+                ((dot-pos (+ (len int-part) exp-n)))
+                (str
+                  (js-string-slice all-digits 0 dot-pos)
+                  "."
+                  (js-string-slice all-digits dot-pos (len all-digits)))))
+            (str "0." (js-string-repeat "0" (- (- 0 exp-n) 1)) all-digits)))))))
+
 (define
   js-number-to-string
   (fn
@@ -1195,7 +1228,16 @@
       ((js-number-is-nan n) "NaN")
       ((= n (js-infinity-value)) "Infinity")
       ((= n (- 0 (js-infinity-value))) "-Infinity")
-      (else (js-normalize-num-str (str n))))))
+      (else
+        (let
+          ((pos-n (if (< n 0) (- 0 n) n)))
+          (let
+            ((s0 (js-normalize-num-str (str pos-n))))
+            (let
+              ((ei (js-string-index-of s0 "e" 0)))
+              (let
+                ((precise (if (< ei 0) s0 (let ((exp-n (js-to-number (js-string-slice s0 (+ ei 1) (len s0))))) (if (and (>= exp-n -6) (<= exp-n 20)) (js-expand-sci-notation (js-string-slice s0 0 ei) exp-n) (if (>= exp-n 0) (str (js-string-slice s0 0 (+ ei 1)) "+" (str exp-n)) s0))))))
+                (if (< n 0) (str "-" precise) precise)))))))))
 
 (define
   js-normalize-num-str
@@ -1296,6 +1338,10 @@
         (= (js-to-number a) b))
       ((= (type-of a) "boolean") (js-loose-eq (js-to-number a) b))
       ((= (type-of b) "boolean") (js-loose-eq a (js-to-number b)))
+      ((and (dict? a) (contains? (keys a) "__js_string_value__"))
+        (js-loose-eq (get a "__js_string_value__") b))
+      ((and (dict? b) (contains? (keys b) "__js_string_value__"))
+        (js-loose-eq a (get b "__js_string_value__")))
       (else false))))
 
 (define js-loose-neq (fn (a b) (not (js-loose-eq a b))))
@@ -3139,6 +3185,23 @@
 
 (dict-set! String "fromCodePoint" js-string-from-code-point)
 
+(dict-set!
+  String
+  "__callable__"
+  (fn
+    (&rest args)
+    (let
+      ((raw (if (= (len args) 0) "" (js-to-string (nth args 0)))))
+      (let
+        ((this-val (js-this)))
+        (if
+          (dict? this-val)
+          (begin
+            (dict-set! this-val "__js_string_value__" raw)
+            (dict-set! this-val "length" (len raw))
+            this-val)
+          raw)))))
+
 (define Boolean {:__callable__ (fn (&rest args) (if (= (len args) 0) false (js-to-boolean (nth args 0))))})
 
 (dict-set!
diff --git a/lib/js/test262-scoreboard.json b/lib/js/test262-scoreboard.json
index 2be221a8..41c21415 100644
--- a/lib/js/test262-scoreboard.json
+++ b/lib/js/test262-scoreboard.json
@@ -1,72 +1,34 @@
 {
   "totals": {
-    "pass": 202,
-    "fail": 85,
-    "skip": 1597,
-    "timeout": 13,
-    "total": 1897,
-    "runnable": 300,
-    "pass_rate": 67.3
+    "pass": 58,
+    "fail": 33,
+    "skip": 1130,
+    "timeout": 9,
+    "total": 1230,
+    "runnable": 100,
+    "pass_rate": 58.0
   },
   "categories": [
-    {
-      "category": "built-ins/Math",
-      "total": 327,
-      "pass": 82,
-      "fail": 17,
-      "skip": 227,
-      "timeout": 1,
-      "pass_rate": 82.0,
-      "top_failures": [
-        [
-          "Test262Error (assertion failed)",
-          17
-        ],
-        [
-          "Timeout",
-          1
-        ]
-      ]
-    },
-    {
-      "category": "built-ins/Number",
-      "total": 340,
-      "pass": 77,
-      "fail": 19,
-      "skip": 240,
-      "timeout": 4,
-      "pass_rate": 77.0,
-      "top_failures": [
-        [
-          "Test262Error (assertion failed)",
-          19
-        ],
-        [
-          "Timeout",
-          4
-        ]
-      ]
-    },
     {
       "category": "built-ins/String",
       "total": 1223,
-      "pass": 43,
-      "fail": 49,
+      "pass": 58,
+      "fail": 33,
       "skip": 1123,
-      "timeout": 8,
-      "pass_rate": 43.0,
+      "timeout": 9,
+      "pass_rate": 58.0,
       "top_failures": [
         [
           "Test262Error (assertion failed)",
-          42
+          28
         ],
         [
           "Timeout",
-          8
+          9
         ],
         [
-          "TypeError: not a function",
-          3
+          "Unhandled: Not callable: \\\\\\",
+          1
         ],
         [
           "ReferenceError (undefined symbol)",
@@ -92,15 +54,15 @@
   "top_failure_modes": [
     [
       "Test262Error (assertion failed)",
-      78
+      28
     ],
     [
       "Timeout",
-      13
+      9
     ],
     [
-      "TypeError: not a function",
-      3
+      "Unhandled: Not callable: \\\\\\",
+      1
     ],
     [
       "ReferenceError (undefined symbol)",
@@ -111,7 +73,7 @@
       1
     ],
     [
-      "Unhandled: Not callable: \\\\\\",
+      "TypeError: not a function",
       1
     ],
     [
@@ -120,6 +82,6 @@
     ]
   ],
   "pinned_commit": "d5e73fc8d2c663554fb72e2380a8c2bc1a318a33",
-  "elapsed_seconds": 102.4,
-  "workers": 2
+  "elapsed_seconds": 37.7,
+  "workers": 7
 }
\ No newline at end of file
diff --git a/lib/js/test262-scoreboard.md b/lib/js/test262-scoreboard.md
index 4a913abe..c4a05764 100644
--- a/lib/js/test262-scoreboard.md
+++ b/lib/js/test262-scoreboard.md
@@ -1,44 +1,32 @@
 # test262 scoreboard
 
 Pinned commit: `d5e73fc8d2c663554fb72e2380a8c2bc1a318a33`
-Wall time: 102.4s
+Wall time: 37.7s
 
-**Total:** 202/300 runnable passed (67.3%). Raw: pass=202 fail=85 skip=1597 timeout=13 total=1897.
+**Total:** 58/100 runnable passed (58.0%). Raw: pass=58 fail=33 skip=1130 timeout=9 total=1230.
 
 ## Top failure modes
 
-- **78x** Test262Error (assertion failed)
-- **13x** Timeout
-- **3x** TypeError: not a function
+- **28x** Test262Error (assertion failed)
+- **9x** Timeout
+- **1x** Unhandled: Not callable: \\\
 - **1x** ReferenceError (undefined symbol)
 - **1x** SyntaxError (parse/unsupported syntax)
-- **1x** Unhandled: Not callable: \\\
+- **1x** TypeError: not a function
 - **1x** Unhandled: js-transpile-binop: unsupported op: >>>\
 
 ## Categories (worst pass-rate first, min 10 runnable)
 
 | Category | Pass | Fail | Skip | Timeout | Total | Pass % |
 |---|---:|---:|---:|---:|---:|---:|
-| built-ins/String | 43 | 49 | 1123 | 8 | 1223 | 43.0% |
-| built-ins/Number | 77 | 19 | 240 | 4 | 340 | 77.0% |
-| built-ins/Math | 82 | 17 | 227 | 1 | 327 | 82.0% |
+| built-ins/String | 58 | 33 | 1123 | 9 | 1223 | 58.0% |
 
 ## Per-category top failures (min 10 runnable, worst first)
 
-### built-ins/String  (43/100 — 43.0%)
+### built-ins/String  (58/100 — 58.0%)
 
-- **42x** Test262Error (assertion failed)
-- **8x** Timeout
-- **3x** TypeError: not a function
+- **28x** Test262Error (assertion failed)
+- **9x** Timeout
+- **1x** Unhandled: Not callable: \\\
 - **1x** ReferenceError (undefined symbol)
 - **1x** SyntaxError (parse/unsupported syntax)
-
-### built-ins/Number  (77/100 — 77.0%)
-
-- **19x** Test262Error (assertion failed)
-- **4x** Timeout
-
-### built-ins/Math  (82/100 — 82.0%)
-
-- **17x** Test262Error (assertion failed)
-- **1x** Timeout