From 7ed757ae5a93f5c0d58626aa420c1ea91c08fdf1 Mon Sep 17 00:00:00 2001
From: Christopher Kintner <kintner@github.com>
Date: Mon, 14 Aug 2023 18:41:08 +0000
Subject: [PATCH] correct off by 1 error in findLast polyfills

---
 src/array-findlast.ts       | 2 +-
 src/array-findlastindex.ts  | 2 +-
 test/array-findlast.js      | 1 +
 test/array-findlastindex.js | 1 +
 4 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/array-findlast.ts b/src/array-findlast.ts
index 54dc30c..14eef66 100644
--- a/src/array-findlast.ts
+++ b/src/array-findlast.ts
@@ -3,7 +3,7 @@ export function arrayFindLast<T>(
   pred: (this: T[], value: T, i: number, array: T[]) => boolean,
   recv = this
 ): T | void {
-  for (let i = this.length; i > 0; i -= 1) {
+  for (let i = this.length - 1; i >= 0; i -= 1) {
     if (pred.call(recv, this[i], i, this)) return this[i]
   }
 }
diff --git a/src/array-findlastindex.ts b/src/array-findlastindex.ts
index fec08fb..d2f6494 100644
--- a/src/array-findlastindex.ts
+++ b/src/array-findlastindex.ts
@@ -3,7 +3,7 @@ export function arrayFindLastIndex<T>(
   pred: (this: T[], value: T, i: number, array: T[]) => boolean,
   recv = this
 ): number {
-  for (let i = this.length; i > 0; i -= 1) {
+  for (let i = this.length - 1; i >= 0; i -= 1) {
     if (pred.call(recv, this[i], i, this)) return i
   }
   return -1
diff --git a/test/array-findlast.js b/test/array-findlast.js
index 57f9935..de11f59 100644
--- a/test/array-findlast.js
+++ b/test/array-findlast.js
@@ -11,6 +11,7 @@ describe('arrayFindLast', () => {
 
   it('returns value that passes truthy', () => {
     expect(arrayFindLast.call([1, 2, 3], v => v === 3)).to.equal(3)
+    expect(arrayFindLast.call([1, 2, 3], v => v === 1)).to.equal(1)
     const arr = [1, 2, 3]
     const recv = {}
     expect(
diff --git a/test/array-findlastindex.js b/test/array-findlastindex.js
index 7248ee1..e599470 100644
--- a/test/array-findlastindex.js
+++ b/test/array-findlastindex.js
@@ -11,6 +11,7 @@ describe('arrayFindLastIndex', () => {
 
   it('returns value that passes truthy', () => {
     expect(arrayFindLastIndex.call([1, 2, 3], v => v === 3)).to.equal(2)
+    expect(arrayFindLastIndex.call([1, 2, 3], v => v === 1)).to.equal(0)
     const arr = [1, 2, 3]
     const recv = {}
     expect(