Merge pull request #5 from alexreardon/array-optimisation

adding performance optimisation: reusing comparision function
alexreardon · Feb 14, 2017 · 9e042eb · 9e042eb
2 parents 8673269 + 801c681
commit 9e042eb
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Showing 2 changed files with 5 additions and 3 deletions.
diff --git 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
@@ -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', () => {