ES6hasInstance

lib/Common/ConfigFlagsList.h

@@ -900,7 +900,7 @@ FLAGPR           (Boolean, ES6, ES6Unscopables         , "Enable ES6 With Statem
 FLAGPR           (Boolean, ES6, ES6RegExSticky         , "Enable ES6 RegEx sticky flag"                             , DEFAULT_CONFIG_ES6RegExSticky)
 FLAGPR_REGOVR_EXP(Boolean, ES6, ES6RegExPrototypeProperties, "Enable ES6 properties on the RegEx prototype"         , DEFAULT_CONFIG_ES6RegExPrototypeProperties)
 FLAGPR_REGOVR_EXP(Boolean, ES6, ES6RegExSymbols        , "Enable ES6 RegExp symbols"                                , DEFAULT_CONFIG_ES6RegExSymbols)
-FLAGPR           (Boolean, ES6, ES6HasInstance         , "Enable ES6 @@hasInstance symbol"                          , DEFAULT_CONFIG_ES6HasInstanceOf)
+FLAGPR_REGOVR_EXP(Boolean, ES6, ES6HasInstance         , "Enable ES6 @@hasInstance symbol"                          , DEFAULT_CONFIG_ES6HasInstanceOf)
 FLAGPR           (Boolean, ES6, ES6Verbose             , "Enable ES6 verbose trace"                                 , DEFAULT_CONFIG_ES6Verbose)
 FLAGPR_REGOVR_EXP(Boolean, ES6, ArrayBufferTransfer    , "Enable ArrayBuffer.transfer"                              , DEFAULT_CONFIG_ArrayBufferTransfer)
 // /ES6 (BLUE+1) features/flags

lib/Runtime/Language/JavascriptOperators.cpp

@@ -6998,7 +6998,8 @@ namespace Js
         if (scriptContext->GetConfig()->IsES6HasInstanceEnabled())
         {
             Var instOfHandler = JavascriptOperators::GetProperty(constructor, PropertyIds::_symbolHasInstance, scriptContext);
-            if (JavascriptOperators::IsUndefinedObject(instOfHandler))
+            if (JavascriptOperators::IsUndefinedObject(instOfHandler) 
+                || instOfHandler == scriptContext->GetBuiltInLibraryFunction(JavascriptFunction::EntryInfo::SymbolHasInstance.GetOriginalEntryPoint()))
             {
                 return JavascriptBoolean::ToVar(constructor->HasInstance(instance, scriptContext, inlineCache), scriptContext);
             }

lib/Runtime/Library/JavascriptFunction.cpp

@@ -2697,7 +2697,7 @@ namespace Js
 
         BOOL result = DynamicObject::SetProperty(propertyId, value, flags, info);
 
-        if (propertyId == PropertyIds::prototype)
+        if (propertyId == PropertyIds::prototype || propertyId == PropertyIds::_symbolHasInstance)
         {
             PropertyValueInfo::SetNoCache(info, this);
             InvalidateConstructorCacheOnPrototypeChange();
@@ -2711,7 +2711,7 @@ namespace Js
     {
         BOOL result = __super::SetPropertyWithAttributes(propertyId, value, attributes, info, flags, possibleSideEffects);
 
-        if (propertyId == PropertyIds::prototype)
+        if (propertyId == PropertyIds::prototype || propertyId == PropertyIds::_symbolHasInstance)
         {
             PropertyValueInfo::SetNoCache(info, this);
             InvalidateConstructorCacheOnPrototypeChange();
@@ -2759,7 +2759,7 @@ namespace Js
 
         BOOL result = DynamicObject::DeleteProperty(propertyId, flags);
 
-        if (result && propertyId == PropertyIds::prototype)
+        if (result && propertyId == PropertyIds::prototype || propertyId == PropertyIds::_symbolHasInstance)
         {
             InvalidateConstructorCacheOnPrototypeChange();
             this->GetScriptContext()->GetThreadContext()->InvalidateIsInstInlineCachesForFunction(this);
@@ -2976,18 +2976,14 @@ namespace Js
 
         Assert(!(callInfo.Flags & CallFlags_New));
 
-        if (args.Info.Count < 2)
-        {
-            JavascriptError::ThrowTypeError(scriptContext, JSERR_FunctionArgument_NeedObject, _u("Function[Symbol.hasInstance]"));
-        }
-
         RecyclableObject * constructor = RecyclableObject::FromVar(args[0]);
-        Var instance = args[1];
-        if (!JavascriptConversion::IsCallable(constructor))
+        if (!JavascriptConversion::IsCallable(constructor) || args.Info.Count < 2)
         {
             return JavascriptBoolean::ToVar(FALSE, scriptContext);
         }
 
+        Var instance = args[1];
+
         Assert(JavascriptProxy::Is(constructor) || JavascriptFunction::Is(constructor));
         return JavascriptBoolean::ToVar(constructor->HasInstance(instance, scriptContext, NULL), scriptContext);
     }

lib/Runtime/Library/JavascriptLibrary.cpp

@@ -2547,6 +2547,7 @@ namespace Js
                                                      library->AddFunctionToLibraryObjectWithName(functionPrototype, PropertyIds::_symbolHasInstance, PropertyIds::_RuntimeFunctionNameId_hasInstance,
                                                                                                  &JavascriptFunction::EntryInfo::SymbolHasInstance, 1));
             functionPrototype->SetWritable(PropertyIds::_symbolHasInstance, false);
+            functionPrototype->SetConfigurable(PropertyIds::_symbolHasInstance, false);
         }
 
         DebugOnly(CheckRegisteredBuiltIns(builtinFuncs, scriptContext));