diff --git a/fxjs/cfxjs_engine.cpp b/fxjs/cfxjs_engine.cpp
index ae1a9bc..95a03dc 100644
--- a/fxjs/cfxjs_engine.cpp
+++ b/fxjs/cfxjs_engine.cpp
@@ -100,7 +100,7 @@
 
 class CFXJS_PerObjectData {
  public:
-  explicit CFXJS_PerObjectData(int nObjDefID) : m_ObjDefID(nObjDefID) {}
+  explicit CFXJS_PerObjectData(uint32_t nObjDefnID) : m_ObjDefnID(nObjDefnID) {}
 
   ~CFXJS_PerObjectData() = default;
 
@@ -123,7 +123,7 @@
         pObj->GetAlignedPointerFromInternalField(1));
   }
 
-  const int m_ObjDefID;
+  const uint32_t m_ObjDefnID;
   std::unique_ptr<CJS_Object> m_pPrivate;
 };
 
@@ -223,7 +223,7 @@
 static v8::Local<v8::ObjectTemplate> GetGlobalObjectTemplate(
     v8::Isolate* pIsolate) {
   FXJS_PerIsolateData* pIsolateData = FXJS_PerIsolateData::Get(pIsolate);
-  for (int i = 0; i < pIsolateData->MaxObjDefinitionID(); ++i) {
+  for (uint32_t i = 1; i <= pIsolateData->CurrentMaxObjDefinitionID(); ++i) {
     CFXJS_ObjDefinition* pObjDef = pIsolateData->ObjDefinitionForID(i);
     if (pObjDef->m_ObjType == FXJSOBJTYPE_GLOBAL)
       return pObjDef->GetInstanceTemplate();
@@ -245,8 +245,8 @@
   v8::Local<v8::Object> obj = value.Get(isolate);
   if (obj.IsEmpty())
     return;
-  int id = CFXJS_Engine::GetObjDefnID(obj);
-  if (id == -1)
+  uint32_t id = CFXJS_Engine::GetObjDefnID(obj);
+  if (id == 0)
     return;
   FXJS_PerIsolateData* pIsolateData = FXJS_PerIsolateData::Get(isolate);
   CFXJS_ObjDefinition* pObjDef = pIsolateData->ObjDefinitionForID(id);
@@ -321,22 +321,24 @@
       pIsolate->GetData(g_embedderDataSlot));
 }
 
-int FXJS_PerIsolateData::MaxObjDefinitionID() const {
-  return pdfium::CollectionSize<int>(m_ObjectDefnArray);
+uint32_t FXJS_PerIsolateData::CurrentMaxObjDefinitionID() const {
+  return pdfium::CollectionSize<uint32_t>(m_ObjectDefnArray);
 }
 
 FXJS_PerIsolateData::FXJS_PerIsolateData(v8::Isolate* pIsolate)
-    : m_pDynamicObjsMap(new V8TemplateMap(pIsolate)) {}
+    : m_pDynamicObjsMap(std::make_unique<V8TemplateMap>(pIsolate)) {}
 
-CFXJS_ObjDefinition* FXJS_PerIsolateData::ObjDefinitionForID(int id) const {
-  return (id >= 0 && id < MaxObjDefinitionID()) ? m_ObjectDefnArray[id].get()
-                                                : nullptr;
+CFXJS_ObjDefinition* FXJS_PerIsolateData::ObjDefinitionForID(
+    uint32_t id) const {
+  return id > 0 && id <= CurrentMaxObjDefinitionID()
+             ? m_ObjectDefnArray[id - 1].get()
+             : nullptr;
 }
 
-int FXJS_PerIsolateData::AssignIDForObjDefinition(
+uint32_t FXJS_PerIsolateData::AssignIDForObjDefinition(
     std::unique_ptr<CFXJS_ObjDefinition> pDefn) {
   m_ObjectDefnArray.push_back(std::move(pDefn));
-  return m_ObjectDefnArray.size() - 1;
+  return CurrentMaxObjDefinitionID();
 }
 
 CFXJS_Engine::CFXJS_Engine() : CFX_V8(nullptr) {}
@@ -346,9 +348,9 @@
 CFXJS_Engine::~CFXJS_Engine() = default;
 
 // static
-int CFXJS_Engine::GetObjDefnID(v8::Local<v8::Object> pObj) {
+uint32_t CFXJS_Engine::GetObjDefnID(v8::Local<v8::Object> pObj) {
   CFXJS_PerObjectData* pData = CFXJS_PerObjectData::GetFromObject(pObj);
-  return pData ? pData->m_ObjDefID : -1;
+  return pData ? pData->m_ObjDefnID : 0;
 }
 
 // static
@@ -369,10 +371,10 @@
   delete pData;
 }
 
-int CFXJS_Engine::DefineObj(const char* sObjName,
-                            FXJSOBJTYPE eObjType,
-                            CFXJS_Engine::Constructor pConstructor,
-                            CFXJS_Engine::Destructor pDestructor) {
+uint32_t CFXJS_Engine::DefineObj(const char* sObjName,
+                                 FXJSOBJTYPE eObjType,
+                                 CFXJS_Engine::Constructor pConstructor,
+                                 CFXJS_Engine::Destructor pDestructor) {
   v8::Isolate::Scope isolate_scope(GetIsolate());
   v8::HandleScope handle_scope(GetIsolate());
   FXJS_PerIsolateData::SetUp(GetIsolate());
@@ -382,7 +384,7 @@
                                             pConstructor, pDestructor));
 }
 
-void CFXJS_Engine::DefineObjMethod(int nObjDefnID,
+void CFXJS_Engine::DefineObjMethod(uint32_t nObjDefnID,
                                    const char* sMethodName,
                                    v8::FunctionCallback pMethodCall) {
   v8::Isolate::Scope isolate_scope(GetIsolate());
@@ -392,7 +394,7 @@
   pObjDef->DefineMethod(NewString(sMethodName), pMethodCall);
 }
 
-void CFXJS_Engine::DefineObjProperty(int nObjDefnID,
+void CFXJS_Engine::DefineObjProperty(uint32_t nObjDefnID,
                                      const char* sPropName,
                                      v8::AccessorGetterCallback pPropGet,
                                      v8::AccessorSetterCallback pPropPut) {
@@ -404,7 +406,7 @@
 }
 
 void CFXJS_Engine::DefineObjAllProperties(
-    int nObjDefnID,
+    uint32_t nObjDefnID,
     v8::GenericNamedPropertyQueryCallback pPropQurey,
     v8::GenericNamedPropertyGetterCallback pPropGet,
     v8::GenericNamedPropertySetterCallback pPropPut,
@@ -416,7 +418,7 @@
   pObjDef->DefineAllProperties(pPropQurey, pPropGet, pPropPut, pPropDel);
 }
 
-void CFXJS_Engine::DefineObjConst(int nObjDefnID,
+void CFXJS_Engine::DefineObjConst(uint32_t nObjDefnID,
                                   const char* sConstName,
                                   v8::Local<v8::Value> pDefault) {
   v8::Isolate::Scope isolate_scope(GetIsolate());
@@ -476,9 +478,9 @@
 
   v8::Context::Scope context_scope(v8Context);
   FXJS_PerIsolateData* pIsolateData = FXJS_PerIsolateData::Get(GetIsolate());
-  int maxID = pIsolateData->MaxObjDefinitionID();
+  uint32_t maxID = pIsolateData->CurrentMaxObjDefinitionID();
   m_StaticObjects.resize(maxID + 1);
-  for (int i = 0; i < maxID; ++i) {
+  for (uint32_t i = 1; i <= maxID; ++i) {
     CFXJS_ObjDefinition* pObjDef = pIsolateData->ObjDefinitionForID(i);
     if (pObjDef->m_ObjType == FXJSOBJTYPE_GLOBAL) {
       CFXJS_PerObjectData::SetInObject(new CFXJS_PerObjectData(i),
@@ -515,7 +517,7 @@
 
   m_ConstArrays.clear();
 
-  for (int i = 0; i < pIsolateData->MaxObjDefinitionID(); ++i) {
+  for (uint32_t i = 1; i <= pIsolateData->CurrentMaxObjDefinitionID(); ++i) {
     CFXJS_ObjDefinition* pObjDef = pIsolateData->ObjDefinitionForID(i);
     v8::Local<v8::Object> pObj;
     if (pObjDef->m_ObjType == FXJSOBJTYPE_GLOBAL) {
@@ -569,7 +571,7 @@
   return pdfium::nullopt;
 }
 
-v8::Local<v8::Object> CFXJS_Engine::NewFXJSBoundObject(int nObjDefnID,
+v8::Local<v8::Object> CFXJS_Engine::NewFXJSBoundObject(uint32_t nObjDefnID,
                                                        FXJSOBJTYPE type) {
   v8::Isolate::Scope isolate_scope(GetIsolate());
   v8::Local<v8::Context> context = GetIsolate()->GetCurrentContext();
@@ -640,7 +642,7 @@
     return nullptr;
 
   CFXJS_ObjDefinition* pObjDef =
-      pIsolateData->ObjDefinitionForID(pProtoData->m_ObjDefID);
+      pIsolateData->ObjDefinitionForID(pProtoData->m_ObjDefnID);
   if (!pObjDef || pObjDef->m_ObjType != FXJSOBJTYPE_GLOBAL)
     return nullptr;
 
diff --git a/fxjs/cfxjs_engine.h b/fxjs/cfxjs_engine.h
index 933c250..d4781b2 100644
--- a/fxjs/cfxjs_engine.h
+++ b/fxjs/cfxjs_engine.h
@@ -51,9 +51,9 @@
   static void SetUp(v8::Isolate* pIsolate);
   static FXJS_PerIsolateData* Get(v8::Isolate* pIsolate);
 
-  int MaxObjDefinitionID() const;
-  CFXJS_ObjDefinition* ObjDefinitionForID(int id) const;
-  int AssignIDForObjDefinition(std::unique_ptr<CFXJS_ObjDefinition> pDefn);
+  uint32_t CurrentMaxObjDefinitionID() const;
+  CFXJS_ObjDefinition* ObjDefinitionForID(uint32_t id) const;
+  uint32_t AssignIDForObjDefinition(std::unique_ptr<CFXJS_ObjDefinition> pDefn);
 
   std::vector<std::unique_ptr<CFXJS_ObjDefinition>> m_ObjectDefnArray;
   std::unique_ptr<V8TemplateMap> m_pDynamicObjsMap;
@@ -83,31 +83,31 @@
       std::function<void(CFXJS_Engine* pEngine, v8::Local<v8::Object> obj)>;
   using Destructor = std::function<void(v8::Local<v8::Object> obj)>;
 
-  static int GetObjDefnID(v8::Local<v8::Object> pObj);
+  static uint32_t GetObjDefnID(v8::Local<v8::Object> pObj);
   static CJS_Object* GetObjectPrivate(v8::Local<v8::Object> pObj);
   static void SetObjectPrivate(v8::Local<v8::Object> pObj,
                                std::unique_ptr<CJS_Object> p);
   static void FreeObjectPrivate(v8::Local<v8::Object> pObj);
 
-  // Always returns a valid, newly-created objDefnID.
-  int DefineObj(const char* sObjName,
-                FXJSOBJTYPE eObjType,
-                Constructor pConstructor,
-                Destructor pDestructor);
+  // Always returns a valid (i.e. non-zero), newly-created objDefnID.
+  uint32_t DefineObj(const char* sObjName,
+                     FXJSOBJTYPE eObjType,
+                     Constructor pConstructor,
+                     Destructor pDestructor);
 
-  void DefineObjMethod(int nObjDefnID,
+  void DefineObjMethod(uint32_t nObjDefnID,
                        const char* sMethodName,
                        v8::FunctionCallback pMethodCall);
-  void DefineObjProperty(int nObjDefnID,
+  void DefineObjProperty(uint32_t nObjDefnID,
                          const char* sPropName,
                          v8::AccessorGetterCallback pPropGet,
                          v8::AccessorSetterCallback pPropPut);
-  void DefineObjAllProperties(int nObjDefnID,
+  void DefineObjAllProperties(uint32_t nObjDefnID,
                               v8::GenericNamedPropertyQueryCallback pPropQurey,
                               v8::GenericNamedPropertyGetterCallback pPropGet,
                               v8::GenericNamedPropertySetterCallback pPropPut,
                               v8::GenericNamedPropertyDeleterCallback pPropDel);
-  void DefineObjConst(int nObjDefnID,
+  void DefineObjConst(uint32_t nObjDefnID,
                       const char* sConstName,
                       v8::Local<v8::Value> pDefault);
   void DefineGlobalMethod(const char* sMethodName,
@@ -123,7 +123,8 @@
   Optional<IJS_Runtime::JS_Error> Execute(const WideString& script);
 
   v8::Local<v8::Object> GetThisObj();
-  v8::Local<v8::Object> NewFXJSBoundObject(int nObjDefnID, FXJSOBJTYPE type);
+  v8::Local<v8::Object> NewFXJSBoundObject(uint32_t nObjDefnID,
+                                           FXJSOBJTYPE type);
   void Error(const WideString& message);
 
   v8::Local<v8::Context> GetV8Context();
diff --git a/fxjs/cfxjs_engine_unittest.cpp b/fxjs/cfxjs_engine_unittest.cpp
index c4644bf..d62e69c 100644
--- a/fxjs/cfxjs_engine_unittest.cpp
+++ b/fxjs/cfxjs_engine_unittest.cpp
@@ -38,7 +38,7 @@
   v8::Isolate::Scope isolate_scope(isolate());
   v8::HandleScope handle_scope(isolate());
 
-  // Object: 0
+  // Object: 1
   engine()->DefineObj(
       "perm", FXJSOBJTYPE_DYNAMIC,
       [](CFXJS_Engine* pEngine, v8::Local<v8::Object> obj) {
@@ -51,7 +51,7 @@
         CFXJS_Engine::SetObjectPrivate(obj, nullptr);
       });
 
-  // Object: 1
+  // Object: 2
   engine()->DefineObj(
       "temp", FXJSOBJTYPE_DYNAMIC,
       [](CFXJS_Engine* pEngine, v8::Local<v8::Object> obj) {
@@ -68,7 +68,7 @@
 
   v8::Context::Scope context_scope(engine()->GetV8Context());
   v8::Local<v8::Object> perm =
-      engine()->NewFXJSBoundObject(0, FXJSOBJTYPE_DYNAMIC);
+      engine()->NewFXJSBoundObject(1, FXJSOBJTYPE_DYNAMIC);
   EXPECT_FALSE(perm.IsEmpty());
   EXPECT_TRUE(perm_created);
   EXPECT_FALSE(perm_destroyed);
@@ -76,7 +76,7 @@
   {
     v8::HandleScope inner_handle_scope(isolate());
     v8::Local<v8::Object> temp =
-        engine()->NewFXJSBoundObject(1, FXJSOBJTYPE_DYNAMIC);
+        engine()->NewFXJSBoundObject(2, FXJSOBJTYPE_DYNAMIC);
     EXPECT_FALSE(temp.IsEmpty());
     EXPECT_TRUE(temp_created);
     EXPECT_FALSE(temp_destroyed);
diff --git a/fxjs/cjs_annot.cpp b/fxjs/cjs_annot.cpp
index 292e586..f13479c 100644
--- a/fxjs/cjs_annot.cpp
+++ b/fxjs/cjs_annot.cpp
@@ -18,12 +18,12 @@
     {"name", get_name_static, set_name_static},
     {"type", get_type_static, set_type_static}};
 
-int CJS_Annot::ObjDefnID = -1;
+uint32_t CJS_Annot::ObjDefnID = 0;
 
 const char CJS_Annot::kName[] = "Annot";
 
 // static
-int CJS_Annot::GetObjDefnID() {
+uint32_t CJS_Annot::GetObjDefnID() {
   return ObjDefnID;
 }
 
diff --git a/fxjs/cjs_annot.h b/fxjs/cjs_annot.h
index ceb2615..4328a90 100644
--- a/fxjs/cjs_annot.h
+++ b/fxjs/cjs_annot.h
@@ -14,7 +14,7 @@
 
 class CJS_Annot final : public CJS_Object {
  public:
-  static int GetObjDefnID();
+  static uint32_t GetObjDefnID();
   static void DefineJSObjects(CFXJS_Engine* pEngine);
 
   CJS_Annot(v8::Local<v8::Object> pObject, CJS_Runtime* pRuntime);
@@ -27,7 +27,7 @@
   JS_STATIC_PROP(type, type, CJS_Annot)
 
  private:
-  static int ObjDefnID;
+  static uint32_t ObjDefnID;
   static const char kName[];
   static const JSPropertySpec PropertySpecs[];
 
diff --git a/fxjs/cjs_app.cpp b/fxjs/cjs_app.cpp
index bc71094..80d9224 100644
--- a/fxjs/cjs_app.cpp
+++ b/fxjs/cjs_app.cpp
@@ -63,12 +63,12 @@
     {"setInterval", setInterval_static},
     {"setTimeOut", setTimeOut_static}};
 
-int CJS_App::ObjDefnID = -1;
+uint32_t CJS_App::ObjDefnID = 0;
 
 const char CJS_App::kName[] = "app";
 
 // static
-int CJS_App::GetObjDefnID() {
+uint32_t CJS_App::GetObjDefnID() {
   return ObjDefnID;
 }
 
diff --git a/fxjs/cjs_app.h b/fxjs/cjs_app.h
index 524a7f0..26184f2 100644
--- a/fxjs/cjs_app.h
+++ b/fxjs/cjs_app.h
@@ -19,7 +19,7 @@
 
 class CJS_App final : public CJS_Object {
  public:
-  static int GetObjDefnID();
+  static uint32_t GetObjDefnID();
   static void DefineJSObjects(CFXJS_Engine* pEngine);
 
   CJS_App(v8::Local<v8::Object> pObject, CJS_Runtime* pRuntime);
@@ -66,7 +66,7 @@
   JS_STATIC_METHOD(setTimeOut, CJS_App)
 
  private:
-  static int ObjDefnID;
+  static uint32_t ObjDefnID;
   static const char kName[];
   static const JSPropertySpec PropertySpecs[];
   static const JSMethodSpec MethodSpecs[];
diff --git a/fxjs/cjs_border.cpp b/fxjs/cjs_border.cpp
index 35204d7..1e8bb10 100644
--- a/fxjs/cjs_border.cpp
+++ b/fxjs/cjs_border.cpp
@@ -13,7 +13,7 @@
     {"i", JSConstSpec::String, 0, "inset"},
     {"u", JSConstSpec::String, 0, "underline"}};
 
-int CJS_Border::ObjDefnID = -1;
+uint32_t CJS_Border::ObjDefnID = 0;
 
 // static
 void CJS_Border::DefineJSObjects(CFXJS_Engine* pEngine) {
diff --git a/fxjs/cjs_border.h b/fxjs/cjs_border.h
index 0a306f7..735821d 100644
--- a/fxjs/cjs_border.h
+++ b/fxjs/cjs_border.h
@@ -16,7 +16,7 @@
   CJS_Border() = delete;
 
  private:
-  static int ObjDefnID;
+  static uint32_t ObjDefnID;
   static const JSConstSpec ConstSpecs[];
 };
 
diff --git a/fxjs/cjs_color.cpp b/fxjs/cjs_color.cpp
index 2b75e75..b9e415e 100644
--- a/fxjs/cjs_color.cpp
+++ b/fxjs/cjs_color.cpp
@@ -33,11 +33,11 @@
 const JSMethodSpec CJS_Color::MethodSpecs[] = {{"convert", convert_static},
                                                {"equal", equal_static}};
 
-int CJS_Color::ObjDefnID = -1;
+uint32_t CJS_Color::ObjDefnID = 0;
 const char CJS_Color::kName[] = "color";
 
 // static
-int CJS_Color::GetObjDefnID() {
+uint32_t CJS_Color::GetObjDefnID() {
   return ObjDefnID;
 }
 
diff --git a/fxjs/cjs_color.h b/fxjs/cjs_color.h
index c758fdc..8953241 100644
--- a/fxjs/cjs_color.h
+++ b/fxjs/cjs_color.h
@@ -15,7 +15,7 @@
 
 class CJS_Color final : public CJS_Object {
  public:
-  static int GetObjDefnID();
+  static uint32_t GetObjDefnID();
   static void DefineJSObjects(CFXJS_Engine* pEngine);
   static v8::Local<v8::Array> ConvertPWLColorToArray(CJS_Runtime* pRuntime,
                                                      const CFX_Color& color);
@@ -42,7 +42,7 @@
   JS_STATIC_METHOD(equal, CJS_Color)
 
  private:
-  static int ObjDefnID;
+  static uint32_t ObjDefnID;
   static const char kName[];
   static const JSPropertySpec PropertySpecs[];
   static const JSMethodSpec MethodSpecs[];
diff --git a/fxjs/cjs_console.cpp b/fxjs/cjs_console.cpp
index c696bbd..9cd0f36 100644
--- a/fxjs/cjs_console.cpp
+++ b/fxjs/cjs_console.cpp
@@ -18,11 +18,11 @@
                                                  {"println", println_static},
                                                  {"show", show_static}};
 
-int CJS_Console::ObjDefnID = -1;
+uint32_t CJS_Console::ObjDefnID = 0;
 const char CJS_Console::kName[] = "console";
 
 // static
-int CJS_Console::GetObjDefnID() {
+uint32_t CJS_Console::GetObjDefnID() {
   return ObjDefnID;
 }
 
diff --git a/fxjs/cjs_console.h b/fxjs/cjs_console.h
index 2bc118a..37dda9d 100644
--- a/fxjs/cjs_console.h
+++ b/fxjs/cjs_console.h
@@ -14,7 +14,7 @@
 
 class CJS_Console final : public CJS_Object {
  public:
-  static int GetObjDefnID();
+  static uint32_t GetObjDefnID();
   static void DefineJSObjects(CFXJS_Engine* pEngine);
 
   CJS_Console(v8::Local<v8::Object> pObject, CJS_Runtime* pRuntime);
@@ -26,7 +26,7 @@
   JS_STATIC_METHOD(show, CJS_Console)
 
  private:
-  static int ObjDefnID;
+  static uint32_t ObjDefnID;
   static const char kName[];
   static const JSMethodSpec MethodSpecs[];
 
diff --git a/fxjs/cjs_display.cpp b/fxjs/cjs_display.cpp
index 71d6c02..a39de17 100644
--- a/fxjs/cjs_display.cpp
+++ b/fxjs/cjs_display.cpp
@@ -12,7 +12,7 @@
     {"noPrint", JSConstSpec::Number, 2, 0},
     {"noView", JSConstSpec::Number, 3, 0}};
 
-int CJS_Display::ObjDefnID = -1;
+uint32_t CJS_Display::ObjDefnID = 0;
 
 // static
 void CJS_Display::DefineJSObjects(CFXJS_Engine* pEngine) {
diff --git a/fxjs/cjs_display.h b/fxjs/cjs_display.h
index 59b6e9c..43236cd 100644
--- a/fxjs/cjs_display.h
+++ b/fxjs/cjs_display.h
@@ -16,7 +16,7 @@
   CJS_Display() = delete;
 
  private:
-  static int ObjDefnID;
+  static uint32_t ObjDefnID;
   static const JSConstSpec ConstSpecs[];
 };
 
diff --git a/fxjs/cjs_document.cpp b/fxjs/cjs_document.cpp
index a7de0be..5c5a10b 100644
--- a/fxjs/cjs_document.cpp
+++ b/fxjs/cjs_document.cpp
@@ -110,11 +110,11 @@
     {"submitForm", submitForm_static},
     {"syncAnnotScan", syncAnnotScan_static}};
 
-int CJS_Document::ObjDefnID = -1;
+uint32_t CJS_Document::ObjDefnID = 0;
 const char CJS_Document::kName[] = "Document";
 
 // static
-int CJS_Document::GetObjDefnID() {
+uint32_t CJS_Document::GetObjDefnID() {
   return ObjDefnID;
 }
 
diff --git a/fxjs/cjs_document.h b/fxjs/cjs_document.h
index 49448fc..ae855f5 100644
--- a/fxjs/cjs_document.h
+++ b/fxjs/cjs_document.h
@@ -22,7 +22,7 @@
 
 class CJS_Document final : public CJS_Object, public Observable {
  public:
-  static int GetObjDefnID();
+  static uint32_t GetObjDefnID();
   static void DefineJSObjects(CFXJS_Engine* pEngine);
 
   CJS_Document(v8::Local<v8::Object> pObject, CJS_Runtime* pRuntime);
@@ -112,7 +112,7 @@
   JS_STATIC_METHOD(syncAnnotScan, CJS_Document)
 
  private:
-  static int ObjDefnID;
+  static uint32_t ObjDefnID;
   static const char kName[];
   static const JSPropertySpec PropertySpecs[];
   static const JSMethodSpec MethodSpecs[];
diff --git a/fxjs/cjs_event.cpp b/fxjs/cjs_event.cpp
index a16ee6c..ceb1201 100644
--- a/fxjs/cjs_event.cpp
+++ b/fxjs/cjs_event.cpp
@@ -34,11 +34,11 @@
     {"value", get_value_static, set_value_static},
     {"willCommit", get_will_commit_static, set_will_commit_static}};
 
-int CJS_Event::ObjDefnID = -1;
+uint32_t CJS_Event::ObjDefnID = 0;
 const char CJS_Event::kName[] = "event";
 
 // static
-int CJS_Event::GetObjDefnID() {
+uint32_t CJS_Event::GetObjDefnID() {
   return ObjDefnID;
 }
 
diff --git a/fxjs/cjs_event.h b/fxjs/cjs_event.h
index b2fa4dc..d2147cf 100644
--- a/fxjs/cjs_event.h
+++ b/fxjs/cjs_event.h
@@ -12,7 +12,7 @@
 
 class CJS_Event final : public CJS_Object {
  public:
-  static int GetObjDefnID();
+  static uint32_t GetObjDefnID();
   static void DefineJSObjects(CFXJS_Engine* pEngine);
 
   CJS_Event(v8::Local<v8::Object> pObject, CJS_Runtime* pRuntime);
@@ -40,7 +40,7 @@
   JS_STATIC_PROP(willCommit, will_commit, CJS_Event)
 
  private:
-  static int ObjDefnID;
+  static uint32_t ObjDefnID;
   static const char kName[];
   static const JSPropertySpec PropertySpecs[];
 
diff --git a/fxjs/cjs_field.cpp b/fxjs/cjs_field.cpp
index 17b6a40..fe762ff 100644
--- a/fxjs/cjs_field.cpp
+++ b/fxjs/cjs_field.cpp
@@ -586,11 +586,11 @@
     {"signatureSign", signatureSign_static},
     {"signatureValidate", signatureValidate_static}};
 
-int CJS_Field::ObjDefnID = -1;
+uint32_t CJS_Field::ObjDefnID = 0;
 const char CJS_Field::kName[] = "Field";
 
 // static
-int CJS_Field::GetObjDefnID() {
+uint32_t CJS_Field::GetObjDefnID() {
   return ObjDefnID;
 }
 
diff --git a/fxjs/cjs_field.h b/fxjs/cjs_field.h
index d772e66..fca91ea 100644
--- a/fxjs/cjs_field.h
+++ b/fxjs/cjs_field.h
@@ -29,7 +29,7 @@
 
 class CJS_Field final : public CJS_Object {
  public:
-  static int GetObjDefnID();
+  static uint32_t GetObjDefnID();
   static void DefineJSObjects(CFXJS_Engine* pEngine);
   static void DoDelay(CPDFSDK_FormFillEnvironment* pFormFillEnv,
                       CJS_DelayData* pData);
@@ -123,7 +123,7 @@
   CJS_Result set_text_color(CJS_Runtime* pRuntime, v8::Local<v8::Value> vp);
 
  private:
-  static int ObjDefnID;
+  static uint32_t ObjDefnID;
   static const char kName[];
   static const JSPropertySpec PropertySpecs[];
   static const JSMethodSpec MethodSpecs[];
diff --git a/fxjs/cjs_font.cpp b/fxjs/cjs_font.cpp
index 0e6e94b..22ff950 100644
--- a/fxjs/cjs_font.cpp
+++ b/fxjs/cjs_font.cpp
@@ -22,7 +22,7 @@
     {"Symbol", JSConstSpec::String, 0, "Symbol"},
     {"ZapfD", JSConstSpec::String, 0, "ZapfDingbats"}};
 
-int CJS_Font::ObjDefnID = -1;
+uint32_t CJS_Font::ObjDefnID = 0;
 
 // static
 void CJS_Font::DefineJSObjects(CFXJS_Engine* pEngine) {
diff --git a/fxjs/cjs_font.h b/fxjs/cjs_font.h
index d3cf159..04b15c0 100644
--- a/fxjs/cjs_font.h
+++ b/fxjs/cjs_font.h
@@ -16,7 +16,7 @@
   CJS_Font() = delete;
 
  private:
-  static int ObjDefnID;
+  static uint32_t ObjDefnID;
   static const JSConstSpec ConstSpecs[];
 };
 
diff --git a/fxjs/cjs_global.cpp b/fxjs/cjs_global.cpp
index a45ccea..3ea04bb 100644
--- a/fxjs/cjs_global.cpp
+++ b/fxjs/cjs_global.cpp
@@ -121,7 +121,7 @@
 const JSMethodSpec CJS_Global::MethodSpecs[] = {
     {"setPersistent", setPersistent_static}};
 
-int CJS_Global::ObjDefnID = -1;
+uint32_t CJS_Global::ObjDefnID = 0;
 
 // static
 void CJS_Global::setPersistent_static(
@@ -183,7 +183,7 @@
 }
 
 // static
-int CJS_Global::GetObjDefnID() {
+uint32_t CJS_Global::GetObjDefnID() {
   return ObjDefnID;
 }
 
diff --git a/fxjs/cjs_global.h b/fxjs/cjs_global.h
index 893a69e..0580dbb 100644
--- a/fxjs/cjs_global.h
+++ b/fxjs/cjs_global.h
@@ -29,7 +29,7 @@
 
 class CJS_Global final : public CJS_Object {
  public:
-  static int GetObjDefnID();
+  static uint32_t GetObjDefnID();
   static void DefineJSObjects(CFXJS_Engine* pEngine);
   static void DefineAllProperties(CFXJS_Engine* pEngine);
 
@@ -71,7 +71,7 @@
     bool bDeleted = false;
   };
 
-  static int ObjDefnID;
+  static uint32_t ObjDefnID;
   static const JSMethodSpec MethodSpecs[];
 
   void UpdateGlobalPersistentVariables();
diff --git a/fxjs/cjs_highlight.cpp b/fxjs/cjs_highlight.cpp
index 4ada397..87fc1a9 100644
--- a/fxjs/cjs_highlight.cpp
+++ b/fxjs/cjs_highlight.cpp
@@ -12,7 +12,7 @@
     {"p", JSConstSpec::String, 0, "push"},
     {"o", JSConstSpec::String, 0, "outline"}};
 
-int CJS_Highlight::ObjDefnID = -1;
+uint32_t CJS_Highlight::ObjDefnID = 0;
 
 // static
 void CJS_Highlight::DefineJSObjects(CFXJS_Engine* pEngine) {
diff --git a/fxjs/cjs_highlight.h b/fxjs/cjs_highlight.h
index efec127..102161a 100644
--- a/fxjs/cjs_highlight.h
+++ b/fxjs/cjs_highlight.h
@@ -16,7 +16,7 @@
   CJS_Highlight() = delete;
 
  private:
-  static int ObjDefnID;
+  static uint32_t ObjDefnID;
   static const JSConstSpec ConstSpecs[];
 };
 
diff --git a/fxjs/cjs_icon.cpp b/fxjs/cjs_icon.cpp
index 80be5c8..f3a2247 100644
--- a/fxjs/cjs_icon.cpp
+++ b/fxjs/cjs_icon.cpp
@@ -9,11 +9,11 @@
 const JSPropertySpec CJS_Icon::PropertySpecs[] = {
     {"name", get_name_static, set_name_static}};
 
-int CJS_Icon::ObjDefnID = -1;
+uint32_t CJS_Icon::ObjDefnID = 0;
 const char CJS_Icon::kName[] = "Icon";
 
 // static
-int CJS_Icon::GetObjDefnID() {
+uint32_t CJS_Icon::GetObjDefnID() {
   return ObjDefnID;
 }
 
diff --git a/fxjs/cjs_icon.h b/fxjs/cjs_icon.h
index 321f508..29f1305 100644
--- a/fxjs/cjs_icon.h
+++ b/fxjs/cjs_icon.h
@@ -12,7 +12,7 @@
 
 class CJS_Icon final : public CJS_Object {
  public:
-  static int GetObjDefnID();
+  static uint32_t GetObjDefnID();
   static void DefineJSObjects(CFXJS_Engine* pEngine);
 
   CJS_Icon(v8::Local<v8::Object> pObject, CJS_Runtime* pRuntime);
@@ -24,7 +24,7 @@
   JS_STATIC_PROP(name, name, CJS_Icon)
 
  private:
-  static int ObjDefnID;
+  static uint32_t ObjDefnID;
   static const char kName[];
   static const JSPropertySpec PropertySpecs[];
 
diff --git a/fxjs/cjs_object.cpp b/fxjs/cjs_object.cpp
index b65c4fc..817b4fa 100644
--- a/fxjs/cjs_object.cpp
+++ b/fxjs/cjs_object.cpp
@@ -10,11 +10,11 @@
 
 // static
 void CJS_Object::DefineConsts(CFXJS_Engine* pEngine,
-                              int objId,
+                              uint32_t nObjDefnID,
                               pdfium::span<const JSConstSpec> consts) {
   for (const auto& item : consts) {
     pEngine->DefineObjConst(
-        objId, item.pName,
+        nObjDefnID, item.pName,
         item.eType == JSConstSpec::Number
             ? pEngine->NewNumber(item.number).As<v8::Value>()
             : pEngine->NewString(item.pStr).As<v8::Value>());
@@ -23,18 +23,19 @@
 
 // static
 void CJS_Object::DefineProps(CFXJS_Engine* pEngine,
-                             int objId,
+                             uint32_t nObjDefnID,
                              pdfium::span<const JSPropertySpec> props) {
   for (const auto& item : props)
-    pEngine->DefineObjProperty(objId, item.pName, item.pPropGet, item.pPropPut);
+    pEngine->DefineObjProperty(nObjDefnID, item.pName, item.pPropGet,
+                               item.pPropPut);
 }
 
 // static
 void CJS_Object::DefineMethods(CFXJS_Engine* pEngine,
-                               int objId,
+                               uint32_t nObjDefnID,
                                pdfium::span<const JSMethodSpec> methods) {
   for (const auto& item : methods)
-    pEngine->DefineObjMethod(objId, item.pName, item.pMethodCall);
+    pEngine->DefineObjMethod(nObjDefnID, item.pName, item.pMethodCall);
 }
 
 CJS_Object::CJS_Object(v8::Local<v8::Object> pObject, CJS_Runtime* pRuntime)
diff --git a/fxjs/cjs_object.h b/fxjs/cjs_object.h
index 5da72ff..e451f25 100644
--- a/fxjs/cjs_object.h
+++ b/fxjs/cjs_object.h
@@ -36,13 +36,13 @@
 class CJS_Object {
  public:
   static void DefineConsts(CFXJS_Engine* pEngine,
-                           int objId,
+                           uint32_t nObjDefnID,
                            pdfium::span<const JSConstSpec> consts);
   static void DefineProps(CFXJS_Engine* pEngine,
-                          int objId,
+                          uint32_t nObjDefnID,
                           pdfium::span<const JSPropertySpec> consts);
   static void DefineMethods(CFXJS_Engine* pEngine,
-                            int objId,
+                            uint32_t nObjDefnID,
                             pdfium::span<const JSMethodSpec> consts);
 
   CJS_Object(v8::Local<v8::Object> pObject, CJS_Runtime* pRuntime);
diff --git a/fxjs/cjs_position.cpp b/fxjs/cjs_position.cpp
index dc9594e..c6e2bfa 100644
--- a/fxjs/cjs_position.cpp
+++ b/fxjs/cjs_position.cpp
@@ -15,7 +15,7 @@
     {"textIconH", JSConstSpec::Number, 5, 0},
     {"overlay", JSConstSpec::Number, 6, 0}};
 
-int CJS_Position::ObjDefnID = -1;
+uint32_t CJS_Position::ObjDefnID = 0;
 
 // static
 void CJS_Position::DefineJSObjects(CFXJS_Engine* pEngine) {
diff --git a/fxjs/cjs_position.h b/fxjs/cjs_position.h
index ae951bf..7319733 100644
--- a/fxjs/cjs_position.h
+++ b/fxjs/cjs_position.h
@@ -16,7 +16,7 @@
   CJS_Position() = delete;
 
  private:
-  static int ObjDefnID;
+  static uint32_t ObjDefnID;
   static const JSConstSpec ConstSpecs[];
 };
 
diff --git a/fxjs/cjs_scalehow.cpp b/fxjs/cjs_scalehow.cpp
index 999949c..2a5fd9f 100644
--- a/fxjs/cjs_scalehow.cpp
+++ b/fxjs/cjs_scalehow.cpp
@@ -10,7 +10,7 @@
     {"proportional", JSConstSpec::Number, 0, 0},
     {"anamorphic", JSConstSpec::Number, 1, 0}};
 
-int CJS_ScaleHow::ObjDefnID = -1;
+uint32_t CJS_ScaleHow::ObjDefnID = 0;
 
 // static
 void CJS_ScaleHow::DefineJSObjects(CFXJS_Engine* pEngine) {
diff --git a/fxjs/cjs_scalehow.h b/fxjs/cjs_scalehow.h
index f8c7eb5..c71cc70 100644
--- a/fxjs/cjs_scalehow.h
+++ b/fxjs/cjs_scalehow.h
@@ -16,7 +16,7 @@
   CJS_ScaleHow() = delete;
 
  private:
-  static int ObjDefnID;
+  static uint32_t ObjDefnID;
   static const JSConstSpec ConstSpecs[];
 };
 
diff --git a/fxjs/cjs_scalewhen.cpp b/fxjs/cjs_scalewhen.cpp
index 5f39153..dc60aac 100644
--- a/fxjs/cjs_scalewhen.cpp
+++ b/fxjs/cjs_scalewhen.cpp
@@ -12,7 +12,7 @@
     {"tooBig", JSConstSpec::Number, 2, 0},
     {"tooSmall", JSConstSpec::Number, 3, 0}};
 
-int CJS_ScaleWhen::ObjDefnID = -1;
+uint32_t CJS_ScaleWhen::ObjDefnID = 0;
 
 // static
 void CJS_ScaleWhen::DefineJSObjects(CFXJS_Engine* pEngine) {
diff --git a/fxjs/cjs_scalewhen.h b/fxjs/cjs_scalewhen.h
index ef046f9..df2affc 100644
--- a/fxjs/cjs_scalewhen.h
+++ b/fxjs/cjs_scalewhen.h
@@ -16,7 +16,7 @@
   CJS_ScaleWhen() = delete;
 
  private:
-  static int ObjDefnID;
+  static uint32_t ObjDefnID;
   static const JSConstSpec ConstSpecs[];
 };
 
diff --git a/fxjs/cjs_style.cpp b/fxjs/cjs_style.cpp
index c068702..9c4de87 100644
--- a/fxjs/cjs_style.cpp
+++ b/fxjs/cjs_style.cpp
@@ -14,7 +14,7 @@
     {"st", JSConstSpec::String, 0, "star"},
     {"sq", JSConstSpec::String, 0, "square"}};
 
-int CJS_Style::ObjDefnID = -1;
+uint32_t CJS_Style::ObjDefnID = 0;
 
 // static
 void CJS_Style::DefineJSObjects(CFXJS_Engine* pEngine) {
diff --git a/fxjs/cjs_style.h b/fxjs/cjs_style.h
index 6e3ee2f..9af4e49 100644
--- a/fxjs/cjs_style.h
+++ b/fxjs/cjs_style.h
@@ -16,7 +16,7 @@
   CJS_Style() = delete;
 
  private:
-  static int ObjDefnID;
+  static uint32_t ObjDefnID;
   static const JSConstSpec ConstSpecs[];
 };
 
diff --git a/fxjs/cjs_timerobj.cpp b/fxjs/cjs_timerobj.cpp
index 5fa1ac3..e19ee19 100644
--- a/fxjs/cjs_timerobj.cpp
+++ b/fxjs/cjs_timerobj.cpp
@@ -9,10 +9,10 @@
 #include "fxjs/global_timer.h"
 #include "fxjs/js_define.h"
 
-int CJS_TimerObj::ObjDefnID = -1;
+uint32_t CJS_TimerObj::ObjDefnID = 0;
 
 // static
-int CJS_TimerObj::GetObjDefnID() {
+uint32_t CJS_TimerObj::GetObjDefnID() {
   return ObjDefnID;
 }
 
diff --git a/fxjs/cjs_timerobj.h b/fxjs/cjs_timerobj.h
index 69effa6..6a1f80f 100644
--- a/fxjs/cjs_timerobj.h
+++ b/fxjs/cjs_timerobj.h
@@ -13,7 +13,7 @@
 
 class CJS_TimerObj final : public CJS_Object {
  public:
-  static int GetObjDefnID();
+  static uint32_t GetObjDefnID();
   static void DefineJSObjects(CFXJS_Engine* pEngine);
 
   CJS_TimerObj(v8::Local<v8::Object> pObject, CJS_Runtime* pRuntime);
@@ -23,7 +23,7 @@
   int GetTimerID() const { return m_nTimerID; }
 
  private:
-  static int ObjDefnID;
+  static uint32_t ObjDefnID;
 
   int m_nTimerID = 0;  // Weak reference to GlobalTimer through global map.
 };
diff --git a/fxjs/cjs_util.cpp b/fxjs/cjs_util.cpp
index 029ed7a..f33ac83 100644
--- a/fxjs/cjs_util.cpp
+++ b/fxjs/cjs_util.cpp
@@ -77,11 +77,11 @@
     {"scand", scand_static},
     {"byteToChar", byteToChar_static}};
 
-int CJS_Util::ObjDefnID = -1;
+uint32_t CJS_Util::ObjDefnID = 0;
 const char CJS_Util::kName[] = "util";
 
 // static
-int CJS_Util::GetObjDefnID() {
+uint32_t CJS_Util::GetObjDefnID() {
   return ObjDefnID;
 }
 
diff --git a/fxjs/cjs_util.h b/fxjs/cjs_util.h
index 6f55b3a..e565520 100644
--- a/fxjs/cjs_util.h
+++ b/fxjs/cjs_util.h
@@ -20,7 +20,7 @@
 
 class CJS_Util final : public CJS_Object {
  public:
-  static int GetObjDefnID();
+  static uint32_t GetObjDefnID();
   static void DefineJSObjects(CFXJS_Engine* pEngine);
 
   CJS_Util(v8::Local<v8::Object> pObject, CJS_Runtime* pRuntime);
@@ -46,7 +46,7 @@
   JS_STATIC_METHOD(byteToChar, CJS_Util)
 
  private:
-  static int ObjDefnID;
+  static uint32_t ObjDefnID;
   static const char kName[];
   static const JSMethodSpec MethodSpecs[];
 
diff --git a/fxjs/cjs_zoomtype.cpp b/fxjs/cjs_zoomtype.cpp
index cdaa2d5..c64be98 100644
--- a/fxjs/cjs_zoomtype.cpp
+++ b/fxjs/cjs_zoomtype.cpp
@@ -15,7 +15,7 @@
     {"pref", JSConstSpec::String, 0, "Preferred"},
     {"refW", JSConstSpec::String, 0, "ReflowWidth"}};
 
-int CJS_Zoomtype::ObjDefnID = -1;
+uint32_t CJS_Zoomtype::ObjDefnID = 0;
 
 // static
 void CJS_Zoomtype::DefineJSObjects(CFXJS_Engine* pEngine) {
diff --git a/fxjs/cjs_zoomtype.h b/fxjs/cjs_zoomtype.h
index de268cd..b27deb3 100644
--- a/fxjs/cjs_zoomtype.h
+++ b/fxjs/cjs_zoomtype.h
@@ -16,7 +16,7 @@
   CJS_Zoomtype() = delete;
 
  private:
-  static int ObjDefnID;
+  static uint32_t ObjDefnID;
   static const JSConstSpec ConstSpecs[];
 };