fix: revert to Uzlopak proposal, is more stable and faster on more cases on node 24

Author: nigrosimone

lib/serializer.js

@@ -95,13 +95,7 @@ module.exports = class Serializer {
 
     if (len === 0) {
       return '""'
-    }
-
-    if (!str.isWellFormed()) {
-      return JSON.stringify(str)
-    }
-
-    if (len < 42) {
+    } else if (len < 42) {
       // magically escape strings for json
       // relying on their charCodeAt
       // everything below 32 needs JSON.stringify()
@@ -120,13 +114,13 @@ module.exports = class Serializer {
           last === -1 && (last = 0)
           result += str.slice(last, i) + '\\'
           last = i
-        } else if (point < 32) {
+        } else if (point < 32 || (point >= 0xd800 && point <= 0xdfff)) {
           // The current character is non-printable characters or a surrogate.
           return JSON.stringify(str)
         }
       }
       return (last === -1 && ('"' + str + '"')) || ('"' + result + str.slice(last) + '"')
-    } else if (len < 5000 && ASCII_ESCAPE.test(str) === false) {
+    } else if (len < 5000 && str.isWellFormed() && ASCII_ESCAPE.test(str) === false) {
       // Only use the regular expression for shorter input. The overhead is otherwise too much.
       return '"' + str + '"'
     } else {