Plus Equals New vs Equals Old Plus New

JavaScript performance comparison

Test case created by scunliffe


I've always used

foo += bar;

for string concatenation but I'm curious how it performs against

foo = foo + bar;

at high volume.

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Testing in unknown unknown
Test Ops/sec
A Plus Equals B
var a = 'hello';
for (var b = 0; b < 25000; b++) {
 a += b;
A Equals A plus B
var a = 'hello';
for (var b = 0; b < 25000; b++) {
 a = a + b;

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1 comment

Mathias Bynens commented :

There’s no need to write out the loop yourself. jsPerf will automatically loop the test code bodies.

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