Add asyncFilter

src/utils/arrays.ts

@@ -328,6 +328,16 @@ export async function asyncSome<T>(values: Iterable<T>, predicate: (value: T) =>
     return false;
 }
 
+/**
+ * Async version of Array.filter.
+ * @param values
+ * @param predicate
+ */
+export async function asyncFilter<T>(values: Array<T>, predicate: (value: T) => Promise<boolean>): Promise<Array<T>> {
+    const results = await Promise.all(values.map(predicate));
+    return values.filter((_, i) => results[i]);
+}
+
 export function filterBoolean<T>(values: Array<T | null | undefined>): T[] {
     return values.filter(Boolean) as T[];
 }

test/unit-tests/utils/arrays-test.ts

@@ -23,6 +23,7 @@ import {
     concat,
     asyncEvery,
     asyncSome,
+    asyncFilter,
 } from "../../../src/utils/arrays";
 
 type TestParams = { input: number[]; output: number[] };
@@ -460,4 +461,15 @@ describe("arrays", () => {
             expect(predicate).toHaveBeenCalledWith(2);
         });
     });
+
+    describe("asyncFilter", () => {
+        it("when called with an empty array, it should return an empty array", async () => {
+            expect(await asyncFilter([], jest.fn().mockResolvedValue(true))).toEqual([]);
+        });
+
+        it("should filter the content", async () => {
+            const predicate = jest.fn().mockImplementation((value) => Promise.resolve(value === 2));
+            expect(await asyncFilter([1, 2, 3], predicate)).toEqual([2]);
+        });
+    });
 });