Add getOwnMetadata

README.md

@@ -37,7 +37,6 @@ import '@abraham/reflection/dist/reflect';
 Reflect.defineMetadata(metadataKey, metadataValue, target);
 ```
 
-
 API
 ----
 
@@ -47,6 +46,7 @@ Reflection does not currently cover the complete API surface of reflect-metadata
 Reflect.decorate(...);
 Reflect.defineMetadata(...);
 Reflect.getMetadata(...);
+Reflect.getOwnMetadata(...);
 Reflect.hasOwnMetadata(...);
 Reflect.metadata(...);
 ```

src/get-own-metadata.test.ts

@@ -0,0 +1,41 @@
+import { Reflection as Reflect } from './index';
+
+const prototype = {};
+const metadataKey = 'key';
+const metadataValue = 'value';
+const target = {};
+const propertyKey = 'name';
+
+test('invalid target', () => {
+  expect(() => Reflect.getOwnMetadata(metadataKey)).toThrow(TypeError);
+});
+
+test('not defined with target', () => {
+  expect(Reflect.getOwnMetadata(metadataKey, target)).toBeUndefined();
+});
+
+test('defined', () => {
+  Reflect.defineMetadata(metadataKey, metadataValue, target);
+  expect(Reflect.getOwnMetadata(metadataKey, target)).toEqual(metadataValue);
+});
+
+test('defined on prototype', () => {
+  const target = Object.create(prototype);
+  Reflect.defineMetadata(metadataKey, metadataValue, prototype);
+  expect(Reflect.getOwnMetadata(metadataKey, target)).toBeUndefined();
+});
+
+test('not defined with property key', () => {
+  expect(Reflect.getOwnMetadata(metadataKey, target, propertyKey)).toBeUndefined();
+});
+
+test('defined with property key', () => {
+  Reflect.defineMetadata(metadataKey, metadataValue, target, propertyKey);
+  expect(Reflect.getOwnMetadata(metadataKey, target, propertyKey)).toEqual(metadataValue);
+});
+
+test('defined on prototype with property key', () => {
+  const target = Object.create(prototype);
+  Reflect.defineMetadata(metadataKey, metadataValue, prototype, propertyKey);
+  expect(Reflect.getOwnMetadata(metadataKey, target, propertyKey)).toBeUndefined();
+});

src/index.ts

@@ -2,6 +2,7 @@ export const Reflection = Object.assign({}, Reflect, {
   decorate,
   defineMetadata,
   getMetadata,
+  getOwnMetadata,
   hasOwnMetadata,
   metadata,
 });
@@ -42,6 +43,10 @@ export function getMetadata(metadataKey: MetadataKey, target: Target, propertyKe
   return ordinaryGetMetadata(metadataKey, target, propertyKey);
 }
 
+export function getOwnMetadata(metadataKey: MetadataKey, target: Target, propertyKey?: PropertyKey) {
+  return ordinaryGetOwnMetadata(metadataKey, target, propertyKey);
+}
+
 export function hasOwnMetadata(metadataKey: MetadataKey, target: Target, propertyKey?: PropertyKey): boolean {
   return ordinaryHasOwnMetadata(metadataKey, target, propertyKey);
 }
@@ -87,6 +92,7 @@ function ordinaryHasOwnMetadata(metadataKey: MetadataKey, target: Target, proper
 }
 
 function ordinaryGetOwnMetadata(metadataKey: MetadataKey, target: Target, propertyKey?: PropertyKey): Function | undefined {
+  if (target === undefined) throw new TypeError();
   const metadataMap = getMetadataMap(target, propertyKey);
   return metadataMap && metadataMap.get(metadataKey);
 }

src/reflect.test.ts

@@ -19,3 +19,7 @@ test('metadata', () => {
 test('hasOwnMetadata', () => {
   expect(Reflect.hasOwnMetadata).toBeDefined();
 });
+
+test('getOwnMetadata', () => {
+  expect(Reflect.getOwnMetadata).toBeDefined();
+});