From 801c68183569abc119830a51003d7af95286af35 Mon Sep 17 00:00:00 2001
From: Alex Reardon <areardon@atlassian.com>
Date: Sun, 12 Feb 2017 21:18:09 +1100
Subject: [PATCH] adding performance optimisation: reusing comparision function

---
 src/index.js  | 6 ++++--
 test/index.js | 2 +-
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/index.js b/src/index.js
index a258f26..4466cbd 100644
--- a/src/index.js
+++ b/src/index.js
@@ -9,12 +9,14 @@ export default function (resultFn: Function, isEqual?: EqualityFn = simpleIsEqua
     let lastResult: any;
     let calledOnce: boolean = false;
 
-    // breaking cache when arguments or context changes
+    const isNewArgEqualToLast = (newArg, index) => isEqual(newArg, lastArgs[index]);
+
+    // breaking cache when context (this) or arguments change
     return function (...newArgs: Array<any>) {
         if (calledOnce &&
             lastThis === this &&
             newArgs.length === lastArgs.length &&
-            lastArgs.every((lastArg, i) => isEqual(lastArg, newArgs[i]))) {
+            newArgs.every(isNewArgEqualToLast)) {
             return lastResult;
         }
 
diff --git a/test/index.js b/test/index.js
index ae8ae8b..e9618ca 100644
--- a/test/index.js
+++ b/test/index.js
@@ -441,7 +441,7 @@ describe('memoizeOne', () => {
             memoizedAdd(1, 4);
 
             expect(equalityStub.calledWith(1, 1)).to.be.true;
-            expect(equalityStub.calledWith(2, 4)).to.be.true;
+            expect(equalityStub.calledWith(4, 2)).to.be.true;
         });
 
         it('should return the previous value without executing the result fn if the equality fn returns true', () => {