Merge pull request #39 from github/kintner/offby1

correct off by 1 error in findLast polyfills

Author: kintner

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]
   }
 }

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

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(

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(