feat(core): adds get method to QueryList (#36907)

Issei Horie · AndrewKushnir · commit a965589eb8f7 · 2020-11-19T12:18:30.000-08:00
This commit adds get method to QueryList. The method returns an item of the internal results by index number. PR Close #29467 PR Close #36907
diff --git a/goldens/public-api/core/core.d.ts b/goldens/public-api/core/core.d.ts
@@ -756,6 +756,7 @@ export declare class QueryList<T> implements Iterable<T> {
     filter(fn: (item: T, index: number, array: T[]) => boolean): T[];
     find(fn: (item: T, index: number, array: T[]) => boolean): T | undefined;
     forEach(fn: (item: T, index: number, array: T[]) => void): void;
+    get(index: number): T | undefined;
     map<U>(fn: (item: T, index: number, array: T[]) => U): U[];
     notifyOnChanges(): void;
     reduce<U>(fn: (prevValue: U, curValue: T, curIndex: number, array: T[]) => U, init: U): U;
diff --git a/packages/core/src/linker/query_list.ts b/packages/core/src/linker/query_list.ts
@@ -63,6 +63,13 @@ export class QueryList<T> implements Iterable<T> {
     if (!proto[symbol]) proto[symbol] = symbolIterator;
   }
 
+  /**
+   * Returns the QueryList entry at `index`.
+   */
+  get(index: number): T|undefined {
+    return this._results[index];
+  }
+
   /**
    * See
    * [Array.map](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/map)
diff --git a/packages/core/test/linker/query_list_spec.ts b/packages/core/test/linker/query_list_spec.ts
@@ -51,6 +51,11 @@ import {beforeEach, describe, expect, it} from '@angular/core/testing/src/testin
       expect(queryList.length).toEqual(2);
     });
 
+    it('should support get', () => {
+      queryList.reset(['one', 'two']);
+      expect(queryList.get(1)).toEqual('two');
+    });
+
     it('should support map', () => {
       queryList.reset(['one', 'two']);
       expect(queryList.map((x) => x)).toEqual(['one', 'two']);
