feat(findLast): add findLast function

Author: djcsdy

index.test.ts

@@ -17,6 +17,7 @@ import {
     filterFirst,
     find,
     findIndex,
+    findLast,
     findLastIndex,
     first,
     fold,
@@ -300,6 +301,13 @@ test("find", t => {
     );
 });
 
+test("findLast", t => {
+    t.is(
+        findLast([1, 2, 3, 4, 5, 2, 1], n => n >= 3),
+        5
+    );
+});
+
 test("maximum", t => {
     t.is(maximum([1, 2, 3]), 3);
     t.is(maximum([1, 2, 3, 4, 3, 2, 1]), 4);

index.ts

@@ -625,6 +625,39 @@ export function findFn<T>(
     return array => find(array, predicate);
 }
 
+export function findLast<T, U extends T>(
+    array: ArrayLike<T>,
+    predicate: (element: T) => element is U
+): U | null;
+export function findLast<T>(
+    array: ArrayLike<T>,
+    predicate: (element: T, index: number) => boolean
+): T | null;
+export function findLast<T>(
+    array: ArrayLike<T>,
+    predicate: (element: T, index: number) => boolean
+): T | null {
+    for (let i = array.length - 1; i >= 0; --i) {
+        const element = array[i] as T;
+        if (predicate(element, i)) {
+            return element;
+        }
+    }
+    return null;
+}
+
+export function findLastFn<T, U extends T>(
+    predicate: (element: T) => element is U
+): (array: ArrayLike<T>) => U | null;
+export function findLastFn<T>(
+    predicate: (element: T, index: number) => boolean
+): (array: ArrayLike<T>) => T | null;
+export function findLastFn<T>(
+    predicate: (element: T, index: number) => boolean
+): (array: ArrayLike<T>) => T | null {
+    return array => findLast(array, predicate);
+}
+
 export function maximum<T extends string | number | boolean>(array: ArrayLike<T>): T | null;
 export function maximum<T>(array: ArrayLike<T>, compare: Comparator<T>): T | null;
 export function maximum<T>(array: ArrayLike<T>, compare?: Comparator<T>): T | null {