Remove some instanceof checks

src/type/definition.js

@@ -302,6 +302,7 @@ function resolveThunk<T>(thunk: Thunk<T>): T {
  *
  */
 export class GraphQLScalarType {
+  kind: 'GraphQLScalarType';
   name: string;
   description: ?string;
   astNode: ?ScalarTypeDefinitionNode;
@@ -422,6 +423,7 @@ export type GraphQLScalarTypeConfig<TInternal, TExternal> = {
  *
  */
 export class GraphQLObjectType {
+  kind: 'GraphQLObjectType';
   name: string;
   description: ?string;
   astNode: ?ObjectTypeDefinitionNode;
@@ -713,6 +715,7 @@ export type GraphQLFieldMap<TSource, TContext> = {
  *
  */
 export class GraphQLInterfaceType {
+  kind: 'GraphQLInterfaceType';
   name: string;
   description: ?string;
   astNode: ?InterfaceTypeDefinitionNode;
@@ -793,6 +796,7 @@ export type GraphQLInterfaceTypeConfig<TSource, TContext> = {
  *
  */
 export class GraphQLUnionType {
+  kind: 'GraphQLUnionType';
   name: string;
   description: ?string;
   astNode: ?UnionTypeDefinitionNode;
@@ -910,6 +914,7 @@ export type GraphQLUnionTypeConfig<TSource, TContext> = {
  * will be used as its internal value.
  */
 export class GraphQLEnumType/* <T> */ {
+  kind: 'GraphQLEnumType';
   name: string;
   description: ?string;
   astNode: ?EnumTypeDefinitionNode;
@@ -1097,6 +1102,7 @@ export type GraphQLEnumValue/* <T> */ = {
  *
  */
 export class GraphQLInputObjectType {
+  kind: 'GraphQLInputObjectType';
   name: string;
   description: ?string;
   astNode: ?InputObjectTypeDefinitionNode;
@@ -1215,6 +1221,7 @@ export type GraphQLInputFieldMap = {
  *
  */
 export class GraphQLList<T: GraphQLType> {
+  kind: 'GraphQLList';
   ofType: T;
 
   constructor(type: T): void {
@@ -1260,6 +1267,7 @@ GraphQLList.prototype.toJSON =
  * Note: the enforcement of non-nullability occurs within the executor.
  */
 export class GraphQLNonNull<T: GraphQLNullableType> {
+  kind: 'GraphQLNonNull';
   ofType: T;
 
   constructor(type: T): void {

src/utilities/astFromValue.js

@@ -60,7 +60,7 @@ export function astFromValue(
   // Ensure flow knows that we treat function params as const.
   const _value = value;
 
-  if (type instanceof GraphQLNonNull) {
+  if (type.kind === 'GraphQLNonNull') {
     const astValue = astFromValue(_value, type.ofType);
     if (astValue && astValue.kind === Kind.NULL) {
       return null;
@@ -80,7 +80,7 @@ export function astFromValue(
 
   // Convert JavaScript array to GraphQL list. If the GraphQLType is a list, but
   // the value is not an array, convert the value using the list's item type.
-  if (type instanceof GraphQLList) {
+  if (type.kind === 'GraphQLList') {
     const itemType = type.ofType;
     if (isCollection(_value)) {
       const valuesNodes = [];
@@ -97,7 +97,7 @@ export function astFromValue(
 
   // Populate the fields of the input object by creating ASTs from each value
   // in the JavaScript object according to the fields in the input type.
-  if (type instanceof GraphQLInputObjectType) {
+  if (type.kind === 'GraphQLInputObjectType') {
     if (_value === null || typeof _value !== 'object') {
       return null;
     }
@@ -118,7 +118,7 @@ export function astFromValue(
   }
 
   invariant(
-    type instanceof GraphQLScalarType || type instanceof GraphQLEnumType,
+    type.kind === 'GraphQLScalarType' || type.kind === 'GraphQLEnumType',
     'Must provide Input Type, cannot use: ' + String(type)
   );
 
@@ -144,7 +144,7 @@ export function astFromValue(
 
   if (typeof serialized === 'string') {
     // Enum types use Enum literals.
-    if (type instanceof GraphQLEnumType) {
+    if (type.kind === 'GraphQLEnumType') {
       return ({ kind: Kind.ENUM, value: serialized }: EnumValueNode);
     }
 

src/utilities/buildASTSchema.js

@@ -99,7 +99,7 @@ function buildWrappedType(
   }
   if (inputTypeNode.kind === Kind.NON_NULL_TYPE) {
     const wrappedType = buildWrappedType(innerType, inputTypeNode.type);
-    invariant(!(wrappedType instanceof GraphQLNonNull), 'No nesting nonnull.');
+    invariant(wrappedType.kind !== 'GraphQLNonNull', 'No nesting nonnull.');
     return new GraphQLNonNull(wrappedType);
   }
   return innerType;
@@ -283,7 +283,7 @@ export function buildASTSchema(ast: DocumentNode): GraphQLSchema {
   function getObjectType(typeNode: TypeDefinitionNode): GraphQLObjectType {
     const type = typeDefNamed(typeNode.name.value);
     invariant(
-      type instanceof GraphQLObjectType,
+      type.kind === 'GraphQLObjectType',
       'AST must provide object type.'
     );
     return (type: any);

src/utilities/buildClientSchema.js

@@ -131,7 +131,7 @@ export function buildClientSchema(
       }
       const nullableType = getType(nullableRef);
       invariant(
-        !(nullableType instanceof GraphQLNonNull),
+        nullableType.kind !== 'GraphQLNonNull',
         'No nesting nonnull.'
       );
       return new GraphQLNonNull(nullableType);
@@ -177,7 +177,7 @@ export function buildClientSchema(
   function getObjectType(typeRef: IntrospectionTypeRef): GraphQLObjectType {
     const type = getType(typeRef);
     invariant(
-      type instanceof GraphQLObjectType,
+      type.kind === 'GraphQLObjectType',
       'Introspection must provide object type for possibleTypes.'
     );
     return type;
@@ -188,7 +188,7 @@ export function buildClientSchema(
   ): GraphQLInterfaceType {
     const type = getType(typeRef);
     invariant(
-      type instanceof GraphQLInterfaceType,
+      type.kind === 'GraphQLInterfaceType',
       'Introspection must provide interface type for interfaces.'
     );
     return type;

src/utilities/extendSchema.js

@@ -100,11 +100,6 @@ export function extendSchema(
   schema: GraphQLSchema,
   documentAST: DocumentNode
 ): GraphQLSchema {
-  invariant(
-    schema instanceof GraphQLSchema,
-    'Must provide valid GraphQLSchema'
-  );
-
   invariant(
     documentAST && documentAST.kind === Kind.DOCUMENT,
     'Must provide valid Document AST'
@@ -151,7 +146,7 @@ export function extendSchema(
             [ def.definition ]
           );
         }
-        if (!(existingType instanceof GraphQLObjectType)) {
+        if (!(existingType.kind === 'GraphQLObjectType')) {
           throw new GraphQLError(
             `Cannot extend non-object type "${extendedTypeName}".`,
             [ def.definition ]
@@ -276,13 +271,13 @@ export function extendSchema(
 
   function getObjectTypeFromAST(node: NamedTypeNode): GraphQLObjectType {
     const type = getTypeFromAST(node);
-    invariant(type instanceof GraphQLObjectType, 'Must be Object type.');
+    invariant(type.kind === 'GraphQLObjectType', 'Must be Object type.');
     return type;
   }
 
   function getInterfaceTypeFromAST(node: NamedTypeNode): GraphQLInterfaceType {
     const type = getTypeFromAST(node);
-    invariant(type instanceof GraphQLInterfaceType, 'Must be Interface type.');
+    invariant(type.kind === 'GraphQLInterfaceType', 'Must be Interface type.');
     return type;
   }
 
@@ -320,13 +315,13 @@ export function extendSchema(
   // Given a type's introspection result, construct the correct
   // GraphQLType instance.
   function extendType(type: GraphQLNamedType): GraphQLNamedType {
-    if (type instanceof GraphQLObjectType) {
+    if (type.kind === 'GraphQLObjectType') {
       return extendObjectType(type);
     }
-    if (type instanceof GraphQLInterfaceType) {
+    if (type.kind === 'GraphQLInterfaceType') {
       return extendInterfaceType(type);
     }
-    if (type instanceof GraphQLUnionType) {
+    if (type.kind === 'GraphQLUnionType') {
       return extendUnionType(type);
     }
     return type;
@@ -441,10 +436,10 @@ export function extendSchema(
   }
 
   function extendFieldType<T: GraphQLType>(typeDef: T): T {
-    if (typeDef instanceof GraphQLList) {
+    if (typeDef.kind === 'GraphQLList') {
       return (new GraphQLList(extendFieldType(typeDef.ofType)): any);
     }
-    if (typeDef instanceof GraphQLNonNull) {
+    if (typeDef.kind === 'GraphQLNonNull') {
       return (new GraphQLNonNull(extendFieldType(typeDef.ofType)): any);
     }
     return getTypeFromDef(typeDef);
@@ -590,7 +585,7 @@ export function extendSchema(
     }
     if (typeNode.kind === Kind.NON_NULL_TYPE) {
       const nullableType = buildInputFieldType(typeNode.type);
-      invariant(!(nullableType instanceof GraphQLNonNull), 'Must be nullable');
+      invariant(nullableType.kind !== 'GraphQLNonNull', 'Must be nullable');
       return new GraphQLNonNull(nullableType);
     }
     return getInputTypeFromAST(typeNode);
@@ -602,7 +597,7 @@ export function extendSchema(
     }
     if (typeNode.kind === Kind.NON_NULL_TYPE) {
       const nullableType = buildOutputFieldType(typeNode.type);
-      invariant(!(nullableType instanceof GraphQLNonNull), 'Must be nullable');
+      invariant(nullableType.kind !== 'GraphQLNonNull', 'Must be nullable');
       return new GraphQLNonNull(nullableType);
     }
     return getOutputTypeFromAST(typeNode);

src/utilities/isValidJSValue.js

@@ -59,7 +59,7 @@ export function isValidJSValue(
   }
 
   // Input objects check each defined field.
-  if (type instanceof GraphQLInputObjectType) {
+  if (type.kind === 'GraphQLInputObjectType') {
     if (typeof value !== 'object' || value === null) {
       return [ `Expected "${type.name}", found not an object.` ];
     }
@@ -87,7 +87,7 @@ export function isValidJSValue(
   }
 
   invariant(
-    type instanceof GraphQLScalarType || type instanceof GraphQLEnumType,
+    type.kind === 'GraphQLScalarType' || type.kind === 'GraphQLEnumType',
     'Must be input type'
   );
 

src/utilities/isValidLiteralValue.js

@@ -71,7 +71,7 @@ export function isValidLiteralValue(
   }
 
   // Input objects check each defined field and look for undefined fields.
-  if (type instanceof GraphQLInputObjectType) {
+  if (type.kind === 'GraphQLInputObjectType') {
     if (valueNode.kind !== Kind.OBJECT) {
       return [ `Expected "${type.name}", found not an object.` ];
     }
@@ -105,7 +105,7 @@ export function isValidLiteralValue(
   }
 
   invariant(
-    type instanceof GraphQLScalarType || type instanceof GraphQLEnumType,
+    type.kind === 'GraphQLScalarType' || type.kind === 'GraphQLEnumType',
     'Must be input type'
   );
 

src/utilities/schemaPrinter.js

@@ -137,18 +137,18 @@ function isSchemaOfCommonNames(schema: GraphQLSchema): boolean {
 }
 
 export function printType(type: GraphQLType): string {
-  if (type instanceof GraphQLScalarType) {
+  if (type.kind === 'GraphQLScalarType') {
     return printScalar(type);
-  } else if (type instanceof GraphQLObjectType) {
+  } else if (type.kind === 'GraphQLObjectType') {
     return printObject(type);
-  } else if (type instanceof GraphQLInterfaceType) {
+  } else if (type.kind === 'GraphQLInterfaceType') {
     return printInterface(type);
-  } else if (type instanceof GraphQLUnionType) {
+  } else if (type.kind === 'GraphQLUnionType') {
     return printUnion(type);
-  } else if (type instanceof GraphQLEnumType) {
+  } else if (type.kind === 'GraphQLEnumType') {
     return printEnum(type);
   }
-  invariant(type instanceof GraphQLInputObjectType);
+  invariant(type.kind === 'GraphQLInputObjectType');
   return printInputObject(type);
 }
 

src/utilities/typeComparators.js

@@ -85,7 +85,7 @@ export function isTypeSubTypeOf(
   // If superType type is an abstract type, maybeSubType type may be a currently
   // possible object type.
   if (isAbstractType(superType) &&
-      maybeSubType instanceof GraphQLObjectType &&
+      maybeSubType.kind === 'GraphQLObjectType' &&
       schema.isPossibleType(superType, maybeSubType)) {
     return true;
   }

src/utilities/valueFromAST.js

@@ -114,7 +114,7 @@ export function valueFromAST(
     return [ coercedValue ];
   }
 
-  if (type instanceof GraphQLInputObjectType) {
+  if (type.kind === 'GraphQLInputObjectType') {
     if (valueNode.kind !== Kind.OBJECT) {
       return; // Invalid: intentionally return no value.
     }
@@ -147,7 +147,7 @@ export function valueFromAST(
   }
 
   invariant(
-    type instanceof GraphQLScalarType || type instanceof GraphQLEnumType,
+    type.kind === 'GraphQLScalarType' || type.kind === 'GraphQLEnumType',
     'Must be input type'
   );