diff --git a/fxjs/cjs_annot.cpp b/fxjs/cjs_annot.cpp
index f4f9669..62fdfb8 100644
--- a/fxjs/cjs_annot.cpp
+++ b/fxjs/cjs_annot.cpp
@@ -46,7 +46,7 @@
 
 CJS_Return Annot::get_hidden(CJS_Runtime* pRuntime) {
   if (!m_pAnnot)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+    return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
 
   CPDF_Annot* pPDFAnnot = ToBAAnnot(m_pAnnot.Get())->GetPDFAnnot();
   return CJS_Return(pRuntime->NewBoolean(
@@ -57,7 +57,7 @@
   // May invalidate m_pAnnot.
   bool bHidden = pRuntime->ToBoolean(vp);
   if (!m_pAnnot)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+    return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
 
   uint32_t flags = ToBAAnnot(m_pAnnot.Get())->GetFlags();
   if (bHidden) {
@@ -78,7 +78,7 @@
 
 CJS_Return Annot::get_name(CJS_Runtime* pRuntime) {
   if (!m_pAnnot)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+    return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
   return CJS_Return(
       pRuntime->NewString(ToBAAnnot(m_pAnnot.Get())->GetAnnotName().c_str()));
 }
@@ -87,7 +87,7 @@
   // May invalidate m_pAnnot.
   WideString annotName = pRuntime->ToWideString(vp);
   if (!m_pAnnot)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+    return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
 
   ToBAAnnot(m_pAnnot.Get())->SetAnnotName(annotName);
   return CJS_Return(true);
@@ -95,7 +95,7 @@
 
 CJS_Return Annot::get_type(CJS_Runtime* pRuntime) {
   if (!m_pAnnot)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+    return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
   return CJS_Return(pRuntime->NewString(
       WideString::FromLocal(CPDF_Annot::AnnotSubtypeToString(
                                 ToBAAnnot(m_pAnnot.Get())->GetAnnotSubtype())
@@ -104,7 +104,7 @@
 }
 
 CJS_Return Annot::set_type(CJS_Runtime* pRuntime, v8::Local<v8::Value> vp) {
-  return CJS_Return(JSGetStringFromID(IDS_STRING_JSREADONLY));
+  return CJS_Return(JSGetStringFromID(JSMessage::kReadOnlyError));
 }
 
 void Annot::SetSDKAnnot(CPDFSDK_BAAnnot* annot) {
diff --git a/fxjs/cjs_app.cpp b/fxjs/cjs_app.cpp
index f013e7e..e89fb2a 100644
--- a/fxjs/cjs_app.cpp
+++ b/fxjs/cjs_app.cpp
@@ -224,7 +224,7 @@
       pRuntime, params, 4, L"cMsg", L"nIcon", L"nType", L"cTitle");
 
   if (!IsTypeKnown(newParams[0]))
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAMERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
 
   CPDFSDK_FormFillEnvironment* pFormFillEnv = pRuntime->GetFormFillEnv();
   if (!pFormFillEnv)
@@ -257,7 +257,7 @@
   if (IsTypeKnown(newParams[3]))
     swTitle = pRuntime->ToWideString(newParams[3]);
   else
-    swTitle = JSGetStringFromID(IDS_STRING_JSALERT);
+    swTitle = JSGetStringFromID(JSMessage::kAlert);
 
   pRuntime->BeginBlock();
   pFormFillEnv->KillFocusAnnot(0);
@@ -275,7 +275,7 @@
     pRuntime->GetFormFillEnv()->JS_appBeep(pRuntime->ToInt32(params[0]));
     return CJS_Return(true);
   }
-  return CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAMERROR));
+  return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
 }
 
 CJS_Return app::findComponent(CJS_Runtime* pRuntime,
@@ -299,12 +299,12 @@
 CJS_Return app::setInterval(CJS_Runtime* pRuntime,
                             const std::vector<v8::Local<v8::Value>>& params) {
   if (params.size() > 2 || params.size() == 0)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAMERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
 
   WideString script =
       params.size() > 0 ? pRuntime->ToWideString(params[0]) : L"";
   if (script.IsEmpty())
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSAFNUMBER_KEYSTROKE));
+    return CJS_Return(JSGetStringFromID(JSMessage::kInvalidInputError));
 
   uint32_t dwInterval = params.size() > 1 ? pRuntime->ToInt32(params[1]) : 1000;
   GlobalTimer* timerRef = new GlobalTimer(this, pRuntime->GetFormFillEnv(),
@@ -327,11 +327,11 @@
 CJS_Return app::setTimeOut(CJS_Runtime* pRuntime,
                            const std::vector<v8::Local<v8::Value>>& params) {
   if (params.size() > 2 || params.size() == 0)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAMERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
 
   WideString script = pRuntime->ToWideString(params[0]);
   if (script.IsEmpty())
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSAFNUMBER_KEYSTROKE));
+    return CJS_Return(JSGetStringFromID(JSMessage::kInvalidInputError));
 
   uint32_t dwTimeOut = params.size() > 1 ? pRuntime->ToInt32(params[1]) : 1000;
   GlobalTimer* timerRef =
@@ -355,7 +355,7 @@
 CJS_Return app::clearTimeOut(CJS_Runtime* pRuntime,
                              const std::vector<v8::Local<v8::Value>>& params) {
   if (params.size() != 1)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAMERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
 
   app::ClearTimerCommon(pRuntime, params[0]);
   return CJS_Return(true);
@@ -364,7 +364,7 @@
 CJS_Return app::clearInterval(CJS_Runtime* pRuntime,
                               const std::vector<v8::Local<v8::Value>>& params) {
   if (params.size() != 1)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAMERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
 
   app::ClearTimerCommon(pRuntime, params[0]);
   return CJS_Return(true);
@@ -434,7 +434,7 @@
                           L"cSubject", L"cMsg");
 
   if (!IsTypeKnown(newParams[0]))
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAMERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
 
   bool bUI = pRuntime->ToBoolean(newParams[0]);
   WideString cTo;
@@ -443,7 +443,7 @@
   } else {
     // cTo parameter required when UI not invoked.
     if (!bUI)
-      return CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAMERROR));
+      return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
   }
 
   WideString cCc;
@@ -531,7 +531,7 @@
                           L"cDefault", L"bPassword", L"cLabel");
 
   if (!IsTypeKnown(newParams[0]))
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAMERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
 
   WideString swQuestion = pRuntime->ToWideString(newParams[0]);
   WideString swTitle = L"PDF";
@@ -557,7 +557,7 @@
       bPassword, pBuff.data(), MAX_INPUT_BYTES);
 
   if (nLengthBytes < 0 || nLengthBytes > MAX_INPUT_BYTES)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAM_TOOLONG));
+    return CJS_Return(JSGetStringFromID(JSMessage::kParamTooLongError));
 
   return CJS_Return(pRuntime->NewString(
       WideString::FromUTF16LE(reinterpret_cast<uint16_t*>(pBuff.data()),
diff --git a/fxjs/cjs_document.cpp b/fxjs/cjs_document.cpp
index 5383c9e..862055a 100644
--- a/fxjs/cjs_document.cpp
+++ b/fxjs/cjs_document.cpp
@@ -142,7 +142,7 @@
 // The total number of fields in document.
 CJS_Return Document::get_num_fields(CJS_Runtime* pRuntime) {
   if (!m_pFormFillEnv)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+    return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
 
   CPDFSDK_InterForm* pInterForm = m_pFormFillEnv->GetInterForm();
   CPDF_InterForm* pPDFForm = pInterForm->GetInterForm();
@@ -152,18 +152,18 @@
 
 CJS_Return Document::set_num_fields(CJS_Runtime* pRuntime,
                                     v8::Local<v8::Value> vp) {
-  return CJS_Return(JSGetStringFromID(IDS_STRING_JSREADONLY));
+  return CJS_Return(JSGetStringFromID(JSMessage::kReadOnlyError));
 }
 
 CJS_Return Document::get_dirty(CJS_Runtime* pRuntime) {
   if (!m_pFormFillEnv)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+    return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
   return CJS_Return(pRuntime->NewBoolean(!!m_pFormFillEnv->GetChangeMark()));
 }
 
 CJS_Return Document::set_dirty(CJS_Runtime* pRuntime, v8::Local<v8::Value> vp) {
   if (!m_pFormFillEnv)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+    return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
 
   pRuntime->ToBoolean(vp) ? m_pFormFillEnv->SetChangeMark()
                           : m_pFormFillEnv->ClearChangeMark();
@@ -180,7 +180,7 @@
 
 CJS_Return Document::get_page_num(CJS_Runtime* pRuntime) {
   if (!m_pFormFillEnv)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+    return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
 
   CPDFSDK_PageView* pPageView = m_pFormFillEnv->GetCurrentView();
   if (!pPageView)
@@ -191,7 +191,7 @@
 CJS_Return Document::set_page_num(CJS_Runtime* pRuntime,
                                   v8::Local<v8::Value> vp) {
   if (!m_pFormFillEnv)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+    return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
 
   int iPageCount = m_pFormFillEnv->GetPageCount();
   int iPageNum = pRuntime->ToInt32(vp);
@@ -241,9 +241,9 @@
 CJS_Return Document::getField(CJS_Runtime* pRuntime,
                               const std::vector<v8::Local<v8::Value>>& params) {
   if (params.size() < 1)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAMERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
   if (!m_pFormFillEnv)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+    return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
 
   WideString wideName = pRuntime->ToWideString(params[0]);
   CPDFSDK_InterForm* pInterForm = m_pFormFillEnv->GetInterForm();
@@ -271,13 +271,13 @@
     CJS_Runtime* pRuntime,
     const std::vector<v8::Local<v8::Value>>& params) {
   if (params.size() != 1)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAMERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
   if (!m_pFormFillEnv)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+    return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
 
   int nIndex = pRuntime->ToInt32(params[0]);
   if (nIndex < 0)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSVALUEERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kValueError));
 
   CPDFSDK_InterForm* pInterForm = m_pFormFillEnv->GetInterForm();
   CPDF_InterForm* pPDFForm = pInterForm->GetInterForm();
@@ -314,9 +314,9 @@
 CJS_Return Document::mailForm(CJS_Runtime* pRuntime,
                               const std::vector<v8::Local<v8::Value>>& params) {
   if (!m_pFormFillEnv)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+    return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
   if (!m_pFormFillEnv->GetPermissions(FPDFPERM_EXTRACT_ACCESS))
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSNOPERMISSION));
+    return CJS_Return(JSGetStringFromID(JSMessage::kPermissionError));
 
   int iLength = params.size();
   bool bUI = iLength > 0 ? pRuntime->ToBoolean(params[0]) : true;
@@ -347,7 +347,7 @@
 CJS_Return Document::print(CJS_Runtime* pRuntime,
                            const std::vector<v8::Local<v8::Value>>& params) {
   if (!m_pFormFillEnv)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+    return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
 
   bool bUI = true;
   int nStart = 0;
@@ -416,13 +416,13 @@
     CJS_Runtime* pRuntime,
     const std::vector<v8::Local<v8::Value>>& params) {
   if (params.size() != 1)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAMERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
   if (!m_pFormFillEnv)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+    return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
 
   if (!(m_pFormFillEnv->GetPermissions(FPDFPERM_MODIFY) ||
         m_pFormFillEnv->GetPermissions(FPDFPERM_ANNOT_FORM)))
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSNOPERMISSION));
+    return CJS_Return(JSGetStringFromID(JSMessage::kPermissionError));
 
   WideString sFieldName = pRuntime->ToWideString(params[0]);
   CPDFSDK_InterForm* pInterForm = m_pFormFillEnv->GetInterForm();
@@ -470,11 +470,11 @@
     CJS_Runtime* pRuntime,
     const std::vector<v8::Local<v8::Value>>& params) {
   if (!m_pFormFillEnv)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+    return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
   if (!(m_pFormFillEnv->GetPermissions(FPDFPERM_MODIFY) ||
         m_pFormFillEnv->GetPermissions(FPDFPERM_ANNOT_FORM) ||
         m_pFormFillEnv->GetPermissions(FPDFPERM_FILL_FORM))) {
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSNOPERMISSION));
+    return CJS_Return(JSGetStringFromID(JSMessage::kPermissionError));
   }
 
   CPDFSDK_InterForm* pInterForm = m_pFormFillEnv->GetInterForm();
@@ -526,9 +526,9 @@
     const std::vector<v8::Local<v8::Value>>& params) {
   int nSize = params.size();
   if (nSize < 1)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAMERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
   if (!m_pFormFillEnv)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+    return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
 
   v8::Local<v8::Array> aFields;
   WideString strURL;
@@ -653,7 +653,7 @@
 
 CJS_Return Document::get_info(CJS_Runtime* pRuntime) {
   if (!m_pFormFillEnv)
-    CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+    CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
 
   const auto* pDictionary = m_pFormFillEnv->GetPDFDocument()->GetInfo();
   if (!pDictionary)
@@ -711,13 +711,13 @@
 }
 
 CJS_Return Document::set_info(CJS_Runtime* pRuntime, v8::Local<v8::Value> vp) {
-  return CJS_Return(JSGetStringFromID(IDS_STRING_JSREADONLY));
+  return CJS_Return(JSGetStringFromID(JSMessage::kReadOnlyError));
 }
 
 CJS_Return Document::getPropertyInternal(CJS_Runtime* pRuntime,
                                          const ByteString& propName) {
   if (!m_pFormFillEnv)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+    return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
 
   CPDF_Dictionary* pDictionary = m_pFormFillEnv->GetPDFDocument()->GetInfo();
   if (!pDictionary)
@@ -730,14 +730,14 @@
                                          v8::Local<v8::Value> vp,
                                          const ByteString& propName) {
   if (!m_pFormFillEnv)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+    return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
 
   CPDF_Dictionary* pDictionary = m_pFormFillEnv->GetPDFDocument()->GetInfo();
   if (!pDictionary)
     return CJS_Return(false);
 
   if (!m_pFormFillEnv->GetPermissions(FPDFPERM_MODIFY))
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSNOPERMISSION));
+    return CJS_Return(JSGetStringFromID(JSMessage::kPermissionError));
 
   WideString csProperty = pRuntime->ToWideString(vp);
   pDictionary->SetNewFor<CPDF_String>(propName, PDF_EncodeText(csProperty),
@@ -766,15 +766,15 @@
 
 CJS_Return Document::get_delay(CJS_Runtime* pRuntime) {
   if (!m_pFormFillEnv)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+    return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
   return CJS_Return(pRuntime->NewBoolean(m_bDelay));
 }
 
 CJS_Return Document::set_delay(CJS_Runtime* pRuntime, v8::Local<v8::Value> vp) {
   if (!m_pFormFillEnv)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+    return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
   if (!m_pFormFillEnv->GetPermissions(FPDFPERM_MODIFY))
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSNOPERMISSION));
+    return CJS_Return(JSGetStringFromID(JSMessage::kPermissionError));
 
   m_bDelay = pRuntime->ToBoolean(vp);
   if (m_bDelay) {
@@ -828,25 +828,25 @@
 
 CJS_Return Document::get_title(CJS_Runtime* pRuntime) {
   if (!m_pFormFillEnv || !m_pFormFillEnv->GetUnderlyingDocument())
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+    return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
   return getPropertyInternal(pRuntime, "Title");
 }
 
 CJS_Return Document::set_title(CJS_Runtime* pRuntime, v8::Local<v8::Value> vp) {
   if (!m_pFormFillEnv || !m_pFormFillEnv->GetUnderlyingDocument())
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+    return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
   return setPropertyInternal(pRuntime, vp, "Title");
 }
 
 CJS_Return Document::get_num_pages(CJS_Runtime* pRuntime) {
   if (!m_pFormFillEnv)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+    return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
   return CJS_Return(pRuntime->NewNumber(m_pFormFillEnv->GetPageCount()));
 }
 
 CJS_Return Document::set_num_pages(CJS_Runtime* pRuntime,
                                    v8::Local<v8::Value> vp) {
-  return CJS_Return(JSGetStringFromID(IDS_STRING_JSREADONLY));
+  return CJS_Return(JSGetStringFromID(JSMessage::kReadOnlyError));
 }
 
 CJS_Return Document::get_external(CJS_Runtime* pRuntime) {
@@ -865,7 +865,7 @@
 
 CJS_Return Document::set_filesize(CJS_Runtime* pRuntime,
                                   v8::Local<v8::Value> vp) {
-  return CJS_Return(JSGetStringFromID(IDS_STRING_JSREADONLY));
+  return CJS_Return(JSGetStringFromID(JSMessage::kReadOnlyError));
 }
 
 CJS_Return Document::get_mouse_x(CJS_Runtime* pRuntime) {
@@ -888,13 +888,13 @@
 
 CJS_Return Document::get_URL(CJS_Runtime* pRuntime) {
   if (!m_pFormFillEnv)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+    return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
   return CJS_Return(
       pRuntime->NewString(m_pFormFillEnv->JS_docGetFilePath().c_str()));
 }
 
 CJS_Return Document::set_URL(CJS_Runtime* pRuntime, v8::Local<v8::Value> vp) {
-  return CJS_Return(JSGetStringFromID(IDS_STRING_JSREADONLY));
+  return CJS_Return(JSGetStringFromID(JSMessage::kReadOnlyError));
 }
 
 CJS_Return Document::get_base_URL(CJS_Runtime* pRuntime) {
@@ -909,7 +909,7 @@
 
 CJS_Return Document::get_calculate(CJS_Runtime* pRuntime) {
   if (!m_pFormFillEnv)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+    return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
 
   CPDFSDK_InterForm* pInterForm = m_pFormFillEnv->GetInterForm();
   return CJS_Return(pRuntime->NewBoolean(!!pInterForm->IsCalculateEnabled()));
@@ -918,7 +918,7 @@
 CJS_Return Document::set_calculate(CJS_Runtime* pRuntime,
                                    v8::Local<v8::Value> vp) {
   if (!m_pFormFillEnv)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+    return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
 
   CPDFSDK_InterForm* pInterForm = m_pFormFillEnv->GetInterForm();
   pInterForm->EnableCalculate(pRuntime->ToBoolean(vp));
@@ -927,7 +927,7 @@
 
 CJS_Return Document::get_document_file_name(CJS_Runtime* pRuntime) {
   if (!m_pFormFillEnv)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+    return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
 
   WideString wsFilePath = m_pFormFillEnv->JS_docGetFilePath();
   size_t i = wsFilePath.GetLength();
@@ -945,18 +945,18 @@
 
 CJS_Return Document::set_document_file_name(CJS_Runtime* pRuntime,
                                             v8::Local<v8::Value> vp) {
-  return CJS_Return(JSGetStringFromID(IDS_STRING_JSREADONLY));
+  return CJS_Return(JSGetStringFromID(JSMessage::kReadOnlyError));
 }
 
 CJS_Return Document::get_path(CJS_Runtime* pRuntime) {
   if (!m_pFormFillEnv)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+    return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
   return CJS_Return(pRuntime->NewString(
       app::SysPathToPDFPath(m_pFormFillEnv->JS_docGetFilePath()).c_str()));
 }
 
 CJS_Return Document::set_path(CJS_Runtime* pRuntime, v8::Local<v8::Value> vp) {
-  return CJS_Return(JSGetStringFromID(IDS_STRING_JSREADONLY));
+  return CJS_Return(JSGetStringFromID(JSMessage::kReadOnlyError));
 }
 
 CJS_Return Document::get_page_window_rect(CJS_Runtime* pRuntime) {
@@ -996,9 +996,9 @@
 CJS_Return Document::getAnnot(CJS_Runtime* pRuntime,
                               const std::vector<v8::Local<v8::Value>>& params) {
   if (params.size() != 2)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAMERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
   if (!m_pFormFillEnv)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+    return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
 
   int nPageNo = pRuntime->ToInt32(params[0]);
   WideString swAnnotName = pRuntime->ToWideString(params[1]);
@@ -1039,7 +1039,7 @@
     CJS_Runtime* pRuntime,
     const std::vector<v8::Local<v8::Value>>& params) {
   if (!m_pFormFillEnv)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+    return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
 
   // TODO(tonikitoo): Add support supported parameters as per
   // the PDF spec.
@@ -1054,7 +1054,7 @@
     CPDFSDK_AnnotIteration annotIteration(pPageView, false);
     for (const auto& pSDKAnnotCur : annotIteration) {
       if (!pSDKAnnotCur)
-        return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+        return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
 
       v8::Local<v8::Object> pObj =
           pRuntime->NewFxDynamicObj(CJS_Annot::GetObjDefnID());
@@ -1104,20 +1104,20 @@
 CJS_Return Document::addIcon(CJS_Runtime* pRuntime,
                              const std::vector<v8::Local<v8::Value>>& params) {
   if (params.size() != 2)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAMERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
 
   WideString swIconName = pRuntime->ToWideString(params[0]);
   if (!params[1]->IsObject())
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSTYPEERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kTypeError));
 
   v8::Local<v8::Object> pJSIcon = pRuntime->ToObject(params[1]);
   if (CFXJS_Engine::GetObjDefnID(pJSIcon) != CJS_Icon::GetObjDefnID())
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSTYPEERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kTypeError));
 
   v8::Local<v8::Object> pObj = pRuntime->ToObject(params[1]);
   CJS_Object* obj = static_cast<CJS_Object*>(pRuntime->GetObjectPrivate(pObj));
   if (!obj->GetEmbedObject())
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSTYPEERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kTypeError));
 
   m_IconNames.push_back(swIconName);
   return CJS_Return(true);
@@ -1148,13 +1148,13 @@
 }
 
 CJS_Return Document::set_icons(CJS_Runtime* pRuntime, v8::Local<v8::Value> vp) {
-  return CJS_Return(JSGetStringFromID(IDS_STRING_JSREADONLY));
+  return CJS_Return(JSGetStringFromID(JSMessage::kReadOnlyError));
 }
 
 CJS_Return Document::getIcon(CJS_Runtime* pRuntime,
                              const std::vector<v8::Local<v8::Value>>& params) {
   if (params.size() != 1)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAMERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
 
   WideString swIconName = pRuntime->ToWideString(params[0]);
   auto it = std::find(m_IconNames.begin(), m_IconNames.end(), swIconName);
@@ -1201,12 +1201,12 @@
     CJS_Runtime* pRuntime,
     const std::vector<v8::Local<v8::Value>>& params) {
   if (!m_pFormFillEnv)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+    return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
 
   if (!(m_pFormFillEnv->GetPermissions(FPDFPERM_MODIFY) ||
         m_pFormFillEnv->GetPermissions(FPDFPERM_ANNOT_FORM) ||
         m_pFormFillEnv->GetPermissions(FPDFPERM_FILL_FORM))) {
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSNOPERMISSION));
+    return CJS_Return(JSGetStringFromID(JSMessage::kPermissionError));
   }
 
   m_pFormFillEnv->GetInterForm()->OnCalculate();
@@ -1226,9 +1226,9 @@
     CJS_Runtime* pRuntime,
     const std::vector<v8::Local<v8::Value>>& params) {
   if (!m_pFormFillEnv)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+    return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
   if (!m_pFormFillEnv->GetPermissions(FPDFPERM_EXTRACT_ACCESS))
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSNOPERMISSION));
+    return CJS_Return(JSGetStringFromID(JSMessage::kPermissionError));
 
   // TODO(tsepez): check maximum allowable params.
 
@@ -1241,7 +1241,7 @@
     return CJS_Return(false);
 
   if (nPageNo < 0 || nPageNo >= pDocument->GetPageCount())
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSVALUEERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kValueError));
 
   CPDF_Dictionary* pPageDict = pDocument->GetPage(nPageNo);
   if (!pPageDict)
@@ -1275,9 +1275,9 @@
     CJS_Runtime* pRuntime,
     const std::vector<v8::Local<v8::Value>>& params) {
   if (!m_pFormFillEnv)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+    return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
   if (!m_pFormFillEnv->GetPermissions(FPDFPERM_EXTRACT_ACCESS))
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+    return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
   return CJS_Return(false);
 }
 
@@ -1285,14 +1285,14 @@
     CJS_Runtime* pRuntime,
     const std::vector<v8::Local<v8::Value>>& params) {
   if (!m_pFormFillEnv)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+    return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
   if (!m_pFormFillEnv->GetPermissions(FPDFPERM_EXTRACT_ACCESS))
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSNOPERMISSION));
+    return CJS_Return(JSGetStringFromID(JSMessage::kPermissionError));
 
   int nPageNo = params.size() > 0 ? pRuntime->ToInt32(params[0]) : 0;
   CPDF_Document* pDocument = m_pFormFillEnv->GetPDFDocument();
   if (nPageNo < 0 || nPageNo >= pDocument->GetPageCount())
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSVALUEERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kValueError));
 
   CPDF_Dictionary* pPageDict = pDocument->GetPage(nPageNo);
   if (!pPageDict)
@@ -1449,9 +1449,9 @@
     CJS_Runtime* pRuntime,
     const std::vector<v8::Local<v8::Value>>& params) {
   if (params.size() != 1)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAMERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
   if (!m_pFormFillEnv)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+    return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
 
   WideString wideName = pRuntime->ToWideString(params[0]);
   CPDF_Document* pDocument = m_pFormFillEnv->GetPDFDocument();
diff --git a/fxjs/cjs_event_context.cpp b/fxjs/cjs_event_context.cpp
index bc908a5..d2f270b 100644
--- a/fxjs/cjs_event_context.cpp
+++ b/fxjs/cjs_event_context.cpp
@@ -32,7 +32,7 @@
   v8::Context::Scope context_scope(context);
 
   if (m_bBusy) {
-    *info = JSGetStringFromID(IDS_STRING_JSBUSY);
+    *info = JSGetStringFromID(JSMessage::kBusyError);
     return false;
   }
 
@@ -43,7 +43,7 @@
   CJS_Runtime::FieldEvent event(m_pEventHandler->TargetName(),
                                 m_pEventHandler->EventType());
   if (!m_pRuntime->AddEventToSet(event)) {
-    *info = JSGetStringFromID(IDS_STRING_JSEVENT);
+    *info = JSGetStringFromID(JSMessage::kDuplicateEventError);
     return false;
   }
 
@@ -55,7 +55,7 @@
   if (nRet < 0)
     *info += sErrorMessage;
   else
-    *info = JSGetStringFromID(IDS_STRING_RUN);
+    *info = JSGetStringFromID(JSMessage::kRunSuccess);
 
   m_pRuntime->RemoveEventFromSet(event);
   m_pEventHandler->Destroy();
diff --git a/fxjs/cjs_field.cpp b/fxjs/cjs_field.cpp
index 51f8c5a..cb8eb6b 100644
--- a/fxjs/cjs_field.cpp
+++ b/fxjs/cjs_field.cpp
@@ -1418,7 +1418,7 @@
   int i = 0;
   for (const auto& pObserved : widgets) {
     if (!pObserved)
-      return CJS_Return(JSGetStringFromID(IDS_STRING_JSBADOBJECT));
+      return CJS_Return(JSGetStringFromID(JSMessage::kBadObjectError));
 
     auto* pWidget = static_cast<CPDFSDK_Widget*>(pObserved.Get());
     CPDFSDK_PageView* pPageView = pWidget->GetPageView();
@@ -1434,7 +1434,7 @@
 }
 
 CJS_Return Field::set_page(CJS_Runtime* pRuntime, v8::Local<v8::Value> vp) {
-  return CJS_Return(JSGetStringFromID(IDS_STRING_JSREADONLY));
+  return CJS_Return(JSGetStringFromID(JSMessage::kReadOnlyError));
 }
 
 CJS_Return Field::get_password(CJS_Runtime* pRuntime) {
diff --git a/fxjs/cjs_global.cpp b/fxjs/cjs_global.cpp
index 3c5c51b..0fef8d5 100644
--- a/fxjs/cjs_global.cpp
+++ b/fxjs/cjs_global.cpp
@@ -346,12 +346,12 @@
     CJS_Runtime* pRuntime,
     const std::vector<v8::Local<v8::Value>>& params) {
   if (params.size() != 2)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAMERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
 
   auto it = m_MapGlobal.find(
       ByteString::FromUnicode(pRuntime->ToWideString(params[0])));
   if (it == m_MapGlobal.end() || it->second->bDeleted)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSNOGLOBAL));
+    return CJS_Return(JSGetStringFromID(JSMessage::kGlobalNotFoundError));
 
   it->second->bPersistent = pRuntime->ToBoolean(params[1]);
   return CJS_Return(true);
diff --git a/fxjs/cjs_publicmethods.cpp b/fxjs/cjs_publicmethods.cpp
index 8c5ab07..8bcfd3c 100644
--- a/fxjs/cjs_publicmethods.cpp
+++ b/fxjs/cjs_publicmethods.cpp
@@ -814,7 +814,7 @@
     const std::vector<v8::Local<v8::Value>>& params) {
 #if _FX_OS_ != _FX_OS_ANDROID_
   if (params.size() != 6)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAMERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
 
   CJS_EventHandler* pEvent =
       pRuntime->GetCurrentEventContext()->GetEventHandler();
@@ -950,7 +950,7 @@
     swTemp.Replace(L",", L".");
     if (!IsNumber(swTemp.c_str())) {
       pEvent->Rc() = false;
-      WideString sError = JSGetStringFromID(IDS_STRING_JSAFNUMBER_KEYSTROKE);
+      WideString sError = JSGetStringFromID(JSMessage::kInvalidInputError);
       AlertIfPossible(pContext, sError.c_str());
       return CJS_Return(sError);
     }
@@ -1028,7 +1028,7 @@
     const std::vector<v8::Local<v8::Value>>& params) {
 #if _FX_OS_ != _FX_OS_ANDROID_
   if (params.size() != 2)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAMERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
 
   CJS_EventHandler* pEvent =
       pRuntime->GetCurrentEventContext()->GetEventHandler();
@@ -1124,7 +1124,7 @@
     CJS_Runtime* pRuntime,
     const std::vector<v8::Local<v8::Value>>& params) {
   if (params.size() != 1)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAMERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
 
   CJS_EventContext* pContext = pRuntime->GetCurrentEventContext();
   CJS_EventHandler* pEvent = pContext->GetEventHandler();
@@ -1149,7 +1149,7 @@
 
   if (std::isnan(dDate)) {
     WideString swMsg;
-    swMsg.Format(JSGetStringFromID(IDS_STRING_JSPARSEDATE).c_str(),
+    swMsg.Format(JSGetStringFromID(JSMessage::kParseDateError).c_str(),
                  sFormat.c_str());
     AlertIfPossible(pContext, swMsg.c_str());
     return CJS_Return(false);
@@ -1237,7 +1237,7 @@
     double dRet = MakeRegularDate(strValue, sFormat, &bWrongFormat);
     if (bWrongFormat || std::isnan(dRet)) {
       WideString swMsg;
-      swMsg.Format(JSGetStringFromID(IDS_STRING_JSPARSEDATE).c_str(),
+      swMsg.Format(JSGetStringFromID(JSMessage::kParseDateError).c_str(),
                    sFormat.c_str());
       AlertIfPossible(pContext, swMsg.c_str());
       pEvent->Rc() = false;
@@ -1251,7 +1251,7 @@
     CJS_Runtime* pRuntime,
     const std::vector<v8::Local<v8::Value>>& params) {
   if (params.size() != 1)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAMERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
 
   int iIndex = pRuntime->ToInt32(params[0]);
   const wchar_t* cFormats[] = {L"m/d",
@@ -1282,7 +1282,7 @@
     CJS_Runtime* pRuntime,
     const std::vector<v8::Local<v8::Value>>& params) {
   if (params.size() != 1)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAMERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
 
   int iIndex = pRuntime->ToInt32(params[0]);
   const wchar_t* cFormats[] = {L"m/d",
@@ -1313,7 +1313,7 @@
     CJS_Runtime* pRuntime,
     const std::vector<v8::Local<v8::Value>>& params) {
   if (params.size() != 1)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAMERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
 
   int iIndex = pRuntime->ToInt32(params[0]);
   const wchar_t* cFormats[] = {L"HH:MM", L"h:MM tt", L"HH:MM:ss",
@@ -1331,7 +1331,7 @@
     CJS_Runtime* pRuntime,
     const std::vector<v8::Local<v8::Value>>& params) {
   if (params.size() != 1)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAMERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
 
   int iIndex = pRuntime->ToInt32(params[0]);
   const wchar_t* cFormats[] = {L"HH:MM", L"h:MM tt", L"HH:MM:ss",
@@ -1362,7 +1362,7 @@
     CJS_Runtime* pRuntime,
     const std::vector<v8::Local<v8::Value>>& params) {
   if (params.size() != 1)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAMERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
 
   CJS_EventHandler* pEvent =
       pRuntime->GetCurrentEventContext()->GetEventHandler();
@@ -1398,7 +1398,7 @@
     CJS_Runtime* pRuntime,
     const std::vector<v8::Local<v8::Value>>& params) {
   if (params.size() < 1)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAMERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
 
   CJS_EventContext* pContext = pRuntime->GetCurrentEventContext();
   CJS_EventHandler* pEvent = pContext->GetEventHandler();
@@ -1422,8 +1422,8 @@
 
     if (iIndexMask != wstrMask.GetLength() ||
         (iIndexMask != valEvent.GetLength() && wstrMask.GetLength() != 0)) {
-      AlertIfPossible(
-          pContext, JSGetStringFromID(IDS_STRING_JSAFNUMBER_KEYSTROKE).c_str());
+      AlertIfPossible(pContext,
+                      JSGetStringFromID(JSMessage::kInvalidInputError).c_str());
       pEvent->Rc() = false;
     }
     return CJS_Return(true);
@@ -1439,14 +1439,14 @@
                         pEvent->SelStart() - pEvent->SelEnd();
   if (combined_len > wstrMask.GetLength()) {
     AlertIfPossible(pContext,
-                    JSGetStringFromID(IDS_STRING_JSPARAM_TOOLONG).c_str());
+                    JSGetStringFromID(JSMessage::kParamTooLongError).c_str());
     pEvent->Rc() = false;
     return CJS_Return(true);
   }
 
   if (iIndexMask >= wstrMask.GetLength() && !wChange.IsEmpty()) {
     AlertIfPossible(pContext,
-                    JSGetStringFromID(IDS_STRING_JSPARAM_TOOLONG).c_str());
+                    JSGetStringFromID(JSMessage::kParamTooLongError).c_str());
     pEvent->Rc() = false;
     return CJS_Return(true);
   }
@@ -1454,7 +1454,7 @@
   for (size_t i = 0; i < wChange.GetLength(); ++i) {
     if (iIndexMask >= wstrMask.GetLength()) {
       AlertIfPossible(pContext,
-                      JSGetStringFromID(IDS_STRING_JSPARAM_TOOLONG).c_str());
+                      JSGetStringFromID(JSMessage::kParamTooLongError).c_str());
       pEvent->Rc() = false;
       return CJS_Return(true);
     }
@@ -1477,7 +1477,7 @@
     CJS_Runtime* pRuntime,
     const std::vector<v8::Local<v8::Value>>& params) {
   if (params.size() != 1)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAMERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
 
   CJS_EventHandler* pEvent =
       pRuntime->GetCurrentEventContext()->GetEventHandler();
@@ -1512,7 +1512,7 @@
     CJS_Runtime* pRuntime,
     const std::vector<v8::Local<v8::Value>>& params) {
   if (params.size() != 1)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAMERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
 
   CJS_EventHandler* pEventHandler =
       pRuntime->GetCurrentEventContext()->GetEventHandler();
@@ -1546,14 +1546,14 @@
     CJS_Runtime* pRuntime,
     const std::vector<v8::Local<v8::Value>>& params) {
   if (params.size() != 2)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAMERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
 
   WideString sValue = pRuntime->ToWideString(params[0]);
   WideString sFormat = pRuntime->ToWideString(params[1]);
   double dDate = MakeRegularDate(sValue, sFormat, nullptr);
   if (std::isnan(dDate)) {
     WideString swMsg;
-    swMsg.Format(JSGetStringFromID(IDS_STRING_JSPARSEDATE).c_str(),
+    swMsg.Format(JSGetStringFromID(JSMessage::kParseDateError).c_str(),
                  sFormat.c_str());
     AlertIfPossible(pRuntime->GetCurrentEventContext(), swMsg.c_str());
     return CJS_Return(false);
@@ -1565,7 +1565,7 @@
     CJS_Runtime* pRuntime,
     const std::vector<v8::Local<v8::Value>>& params) {
   if (params.size() != 3)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAMERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
 
   return CJS_Return(pRuntime->NewNumber(static_cast<double>(AF_Simple(
       pRuntime->ToWideString(params[0]).c_str(), pRuntime->ToDouble(params[1]),
@@ -1576,7 +1576,7 @@
     CJS_Runtime* pRuntime,
     const std::vector<v8::Local<v8::Value>>& params) {
   if (params.size() != 1)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAMERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
 
   WideString ws = pRuntime->ToWideString(params[0]);
   ws.Replace(L",", L".");
@@ -1592,10 +1592,10 @@
     CJS_Runtime* pRuntime,
     const std::vector<v8::Local<v8::Value>>& params) {
   if (params.size() != 2)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAMERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
 
   if ((params[1].IsEmpty() || !params[1]->IsArray()) && !params[1]->IsString())
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAMERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
 
   CPDFSDK_InterForm* pReaderInterForm =
       pRuntime->GetFormFillEnv()->GetInterForm();
@@ -1687,7 +1687,7 @@
     CJS_Runtime* pRuntime,
     const std::vector<v8::Local<v8::Value>>& params) {
   if (params.size() != 4)
-    CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAMERROR));
+    CJS_Return(JSGetStringFromID(JSMessage::kParamError));
 
   CJS_EventContext* pContext = pRuntime->GetCurrentEventContext();
   CJS_EventHandler* pEvent = pContext->GetEventHandler();
@@ -1706,16 +1706,16 @@
 
   if (bGreaterThan && bLessThan) {
     if (dEentValue < dGreaterThan || dEentValue > dLessThan)
-      swMsg.Format(JSGetStringFromID(IDS_STRING_JSRANGE1).c_str(),
+      swMsg.Format(JSGetStringFromID(JSMessage::kRangeBetweenError).c_str(),
                    pRuntime->ToWideString(params[1]).c_str(),
                    pRuntime->ToWideString(params[3]).c_str());
   } else if (bGreaterThan) {
     if (dEentValue < dGreaterThan)
-      swMsg.Format(JSGetStringFromID(IDS_STRING_JSRANGE2).c_str(),
+      swMsg.Format(JSGetStringFromID(JSMessage::kRangeGreaterError).c_str(),
                    pRuntime->ToWideString(params[1]).c_str());
   } else if (bLessThan) {
     if (dEentValue > dLessThan)
-      swMsg.Format(JSGetStringFromID(IDS_STRING_JSRANGE3).c_str(),
+      swMsg.Format(JSGetStringFromID(JSMessage::kRangeLessError).c_str(),
                    pRuntime->ToWideString(params[3]).c_str());
   }
 
@@ -1730,7 +1730,7 @@
     CJS_Runtime* pRuntime,
     const std::vector<v8::Local<v8::Value>>& params) {
   if (params.size() != 1)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAMERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
 
   WideString str = pRuntime->ToWideString(params[0]);
   if (str.GetLength() > 0 && (str[0] == L'.' || str[0] == L','))
diff --git a/fxjs/cjs_util.cpp b/fxjs/cjs_util.cpp
index 7a80700..9fc1093 100644
--- a/fxjs/cjs_util.cpp
+++ b/fxjs/cjs_util.cpp
@@ -144,11 +144,13 @@
     return CJS_Return(false);
 
   if (params[1].IsEmpty() || !params[1]->IsDate())
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSPRINT1));
+    return CJS_Return(JSGetStringFromID(JSMessage::kSecondParamNotDateError));
 
   v8::Local<v8::Date> v8_date = params[1].As<v8::Date>();
-  if (v8_date.IsEmpty() || std::isnan(pRuntime->ToDouble(v8_date)))
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSPRINT2));
+  if (v8_date.IsEmpty() || std::isnan(pRuntime->ToDouble(v8_date))) {
+    return CJS_Return(
+        JSGetStringFromID(JSMessage::kSecondParamInvalidDateError));
+  }
 
   double date = JS_LocalTime(pRuntime->ToDouble(v8_date));
   int year = JS_GetYearFromTime(date);
@@ -174,7 +176,7 @@
                         hour, min, sec);
         break;
       default:
-        return CJS_Return(JSGetStringFromID(IDS_STRING_JSVALUEERROR));
+        return CJS_Return(JSGetStringFromID(JSMessage::kValueError));
     }
 
     return CJS_Return(pRuntime->NewString(swResult.c_str()));
@@ -183,7 +185,7 @@
   if (params[0]->IsString()) {
     // We don't support XFAPicture at the moment.
     if (iSize > 2 && pRuntime->ToBoolean(params[2]))
-      return CJS_Return(JSGetStringFromID(IDS_STRING_JSNOTSUPPORT));
+      return CJS_Return(JSGetStringFromID(JSMessage::kNotSupportedError));
 
     // Convert PDF-style format specifiers to wcsftime specifiers. Remove any
     // pre-existing %-directives before inserting our own.
@@ -204,7 +206,7 @@
     }
 
     if (year < 0)
-      return CJS_Return(JSGetStringFromID(IDS_STRING_JSVALUEERROR));
+      return CJS_Return(JSGetStringFromID(JSMessage::kValueError));
 
     static const TbConvertAdditional cTableAd[] = {
         {L"m", month}, {L"d", day},
@@ -244,13 +246,13 @@
     return CJS_Return(pRuntime->NewString(cFormat.c_str()));
   }
 
-  return CJS_Return(JSGetStringFromID(IDS_STRING_JSTYPEERROR));
+  return CJS_Return(JSGetStringFromID(JSMessage::kTypeError));
 }
 
 CJS_Return util::printx(CJS_Runtime* pRuntime,
                         const std::vector<v8::Local<v8::Value>>& params) {
   if (params.size() < 2)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAMERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
 
   return CJS_Return(
       pRuntime->NewString(printx(pRuntime->ToWideString(params[0]),
@@ -375,11 +377,11 @@
 CJS_Return util::byteToChar(CJS_Runtime* pRuntime,
                             const std::vector<v8::Local<v8::Value>>& params) {
   if (params.size() < 1)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSPARAMERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
 
   int arg = pRuntime->ToInt32(params[0]);
   if (arg < 0 || arg > 255)
-    return CJS_Return(JSGetStringFromID(IDS_STRING_JSVALUEERROR));
+    return CJS_Return(JSGetStringFromID(JSMessage::kValueError));
 
   WideString wStr(static_cast<wchar_t>(arg));
   return CJS_Return(pRuntime->NewString(wStr.c_str()));
diff --git a/fxjs/js_resources.cpp b/fxjs/js_resources.cpp
index c7ed06f..b23103a 100644
--- a/fxjs/js_resources.cpp
+++ b/fxjs/js_resources.cpp
@@ -6,52 +6,52 @@
 
 #include "fxjs/js_resources.h"
 
-WideString JSGetStringFromID(uint32_t id) {
-  switch (id) {
-    case IDS_STRING_JSALERT:
+WideString JSGetStringFromID(JSMessage msg) {
+  switch (msg) {
+    case JSMessage::kAlert:
       return L"Alert";
-    case IDS_STRING_JSPARAMERROR:
+    case JSMessage::kParamError:
       return L"Incorrect number of parameters passed to function.";
-    case IDS_STRING_JSAFNUMBER_KEYSTROKE:
+    case JSMessage::kInvalidInputError:
       return L"The input value is invalid.";
-    case IDS_STRING_JSPARAM_TOOLONG:
+    case JSMessage::kParamTooLongError:
       return L"The input value is too long.";
-    case IDS_STRING_JSPARSEDATE:
+    case JSMessage::kParseDateError:
       return L"The input value can't be parsed as a valid date/time (%s).";
-    case IDS_STRING_JSRANGE1:
+    case JSMessage::kRangeBetweenError:
       return L"The input value must be greater than or equal to %s"
              L" and less than or equal to %s.";
-    case IDS_STRING_JSRANGE2:
+    case JSMessage::kRangeGreaterError:
       return L"The input value must be greater than or equal to %s.";
-    case IDS_STRING_JSRANGE3:
+    case JSMessage::kRangeLessError:
       return L"The input value must be less than or equal to %s.";
-    case IDS_STRING_JSNOTSUPPORT:
+    case JSMessage::kNotSupportedError:
       return L"Operation not supported.";
-    case IDS_STRING_JSBUSY:
+    case JSMessage::kBusyError:
       return L"System is busy.";
-    case IDS_STRING_JSEVENT:
+    case JSMessage::kDuplicateEventError:
       return L"Duplicate formfield event found.";
-    case IDS_STRING_RUN:
+    case JSMessage::kRunSuccess:
       return L"Script ran successfully.";
-    case IDS_STRING_JSPRINT1:
+    case JSMessage::kSecondParamNotDateError:
       return L"The second parameter can't be converted to a Date.";
-    case IDS_STRING_JSPRINT2:
+    case JSMessage::kSecondParamInvalidDateError:
       return L"The second parameter is an invalid Date!";
-    case IDS_STRING_JSNOGLOBAL:
+    case JSMessage::kGlobalNotFoundError:
       return L"Global value not found.";
-    case IDS_STRING_JSREADONLY:
+    case JSMessage::kReadOnlyError:
       return L"Cannot assign to readonly property.";
-    case IDS_STRING_JSTYPEERROR:
+    case JSMessage::kTypeError:
       return L"Incorrect parameter type.";
-    case IDS_STRING_JSVALUEERROR:
+    case JSMessage::kValueError:
       return L"Incorrect parameter value.";
-    case IDS_STRING_JSNOPERMISSION:
+    case JSMessage::kPermissionError:
       return L"Permission denied.";
-    case IDS_STRING_JSBADOBJECT:
+    case JSMessage::kBadObjectError:
       return L"Object no longer exists.";
-    default:
-      return L"";
   }
+  NOTREACHED();
+  return L"";
 }
 
 WideString JSFormatErrorString(const char* class_name,
diff --git a/fxjs/js_resources.h b/fxjs/js_resources.h
index 9f65548..728ec22 100644
--- a/fxjs/js_resources.h
+++ b/fxjs/js_resources.h
@@ -9,28 +9,30 @@
 
 #include "core/fxcrt/widestring.h"
 
-#define IDS_STRING_JSALERT 25613
-#define IDS_STRING_JSPARAMERROR 25614
-#define IDS_STRING_JSAFNUMBER_KEYSTROKE 25615
-#define IDS_STRING_JSPARAM_TOOLONG 25617
-#define IDS_STRING_JSPARSEDATE 25618
-#define IDS_STRING_JSRANGE1 25619
-#define IDS_STRING_JSRANGE2 25620
-#define IDS_STRING_JSRANGE3 25621
-#define IDS_STRING_JSNOTSUPPORT 25627
-#define IDS_STRING_JSBUSY 25628
-#define IDS_STRING_JSEVENT 25629
-#define IDS_STRING_RUN 25630
-#define IDS_STRING_JSPRINT1 25632
-#define IDS_STRING_JSPRINT2 25633
-#define IDS_STRING_JSNOGLOBAL 25635
-#define IDS_STRING_JSREADONLY 25636
-#define IDS_STRING_JSTYPEERROR 25637
-#define IDS_STRING_JSVALUEERROR 25638
-#define IDS_STRING_JSNOPERMISSION 25639
-#define IDS_STRING_JSBADOBJECT 25640
+enum class JSMessage {
+  kRunSuccess = 0,
+  kAlert,
+  kParamError,
+  kInvalidInputError,
+  kParamTooLongError,
+  kParseDateError,
+  kRangeBetweenError,
+  kRangeGreaterError,
+  kRangeLessError,
+  kNotSupportedError,
+  kBusyError,
+  kDuplicateEventError,
+  kSecondParamNotDateError,
+  kSecondParamInvalidDateError,
+  kGlobalNotFoundError,
+  kReadOnlyError,
+  kTypeError,
+  kValueError,
+  kPermissionError,
+  kBadObjectError
+};
 
-WideString JSGetStringFromID(uint32_t id);
+WideString JSGetStringFromID(JSMessage msg);
 WideString JSFormatErrorString(const char* class_name,
                                const char* property_name,
                                const WideString& details);