Benchmark: Array.prototype.concat vs splice for joining two arrays

Tests:

immutable with concat
var a = [ "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello" ] var b = [ "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello" ] var other = a.concat(b)
direct mutation with splice + spread
var a = [ "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello" ] var b = [ "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello" ] a.splice(0, a.length, ...b);

Rendered benchmark preparation results:

Previous results

Test case name	Result
immutable with concat
direct mutation with splice + spread

ⓘ Get performance results from real users on your website with Request Metrics.

Latest run results:

Run details: (Test run date: 13 days ago)

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:129.0) Gecko/20100101 Firefox/129.0

Browser/OS: Firefox 129 on Linux

Test name	Executions per second
immutable with concat	5574129.0 Ops/sec
direct mutation with splice + spread	1944764.0 Ops/sec

Array.prototype.concat vs splice for joining two arrays (version: 0)