CODEWITHSUNDEEP
javascriptperformance
Christophe Debove
Christophe Debove

Reputation: 6296

is concat faster or slower than push

For this code I want to know in javascript what is the best approach?

var output = foo +";"+bar;

or

var output = new Array(foo,bar).join(";");

Upvotes: 9

Views: 10928

Answers (3)

Minko Gechev
Minko Gechev

Reputation: 25682

There are many test cases in http://jsperf.com/ (for example http://jsperf.com/joint-vs-concat). There you can check which is slower. In my experience depends on the user's browser (to be more exact - JS engine).

Upvotes: 1

zafus_coder
zafus_coder

Reputation: 4591

According to me String concatenation is faster then array joins . saw these test cases

http://jsperf.com/array-join-vs-string-connect
http://jsperf.com/join-concat/2

Upvotes: 0

Denys Séguret
Denys Séguret

Reputation: 382102

It doesn't really matter.

There were blogs promoting the first one or the second one, depending on their benchmarks.

But the truth is that javascript engines are heavily optimized and changing, so you won't find a big reproducible and cross-browser difference.

Choose the most readable. Generally it's the first one.

If you really do a loop with 10000 times this push, benchmark it on your customer browsers in your real code, and choose the best but only if there is a significative difference. Don't forget that javascript is fast.

Upvotes: 14

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