feat(asyncNoneNullOnce): add asyncNoneNullOnce function

Author: djcsdy

index.test.ts

@@ -32,6 +32,7 @@ import {
     asyncMaximumOnce,
     asyncMinimumByOnce,
     asyncMinimumOnce,
+    asyncNoneNullOnce,
     asyncNotEmptyOnce,
     asyncNotEqualOnce,
     asyncOnlyOnce,
@@ -581,3 +582,10 @@ test("asyncConcatMapOnce", async t => {
         ["1", "2", "3", "4", "5", "6"]
     );
 });
+
+test("asyncNoneNullOnce", async t => {
+    t.deepEqual(await asyncNoneNullOnce(asyncIterator([1, 2, 3])), [1, 2, 3]);
+    t.is(await asyncNoneNullOnce(asyncIterator([1, null, 3])), null);
+    t.is(await asyncNoneNullOnce(asyncIterator([undefined, 2, 3])), null);
+    t.deepEqual(await asyncNoneNullOnce(asyncIterator([])), []);
+});

index.ts

@@ -1054,3 +1054,20 @@ export function asyncConcatMapOnceFn<T, U>(
 ): (iterator: AsyncIteratorLike<T>) => AsyncIterator<U> {
     return iterator => asyncConcatMapOnce(iterator, f);
 }
+
+export async function asyncNoneNullOnce<T>(
+    iterator: AsyncIteratorLike<T | null | undefined>
+): Promise<T[] | null> {
+    const array: T[] = [];
+    const it = asyncIterator(iterator);
+    let element = await it.next();
+    while (element.done !== true) {
+        if (element.value == null) {
+            return null;
+        } else {
+            array.push(element.value);
+        }
+        element = await it.next();
+    }
+    return array;
+}