feat(lastIndexOf): add lastIndexOf function

(cherry picked from commit 6013891)

Author: djcsdy

index.test.ts

@@ -31,6 +31,7 @@ import {
     keyFirstBy,
     keyLastBy,
     last,
+    lastIndexOf,
     map,
     mapKeyBy,
     mapKeyFirstBy,
@@ -273,6 +274,10 @@ test("contains", t => {
     t.false(contains([1, 2, 3], 0));
 });
 
+test("lastIndexOf", t => {
+    t.is(lastIndexOf([1, 2, 3, 4, 3, 2, 1], 3), 4);
+});
+
 test("findIndex", t => {
     t.is(
         findIndex([1, 2, 3, 4, 3, 2, 1], n => n >= 3),

index.ts

@@ -532,6 +532,19 @@ export function indexOfFn<T>(value: T): (array: ArrayLike<T>) => number | null {
     return array => indexOf(array, value);
 }
 
+export function lastIndexOf<T>(array: ArrayLike<T>, value: T): number | null {
+    for (let i = array.length - 1; i >= 0; --i) {
+        if (array[i] === value) {
+            return i;
+        }
+    }
+    return null;
+}
+
+export function lastIndexOfFn<T>(value: T): (array: ArrayLike<T>) => number | null {
+    return array => lastIndexOf(array, value);
+}
+
 export function findIndex<T>(
     array: ArrayLike<T>,
     predicate: (element: T, index: number) => boolean