Run results for: arity 3 string join vs concat vs plus with separator

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.77 Safari/537.36

Browser: Chrome 91

Operating system: Linux

Device Platform: Desktop

Date tested: 3 years ago

Test name	Executions per second
Join string parts	5952797.5 Ops/sec
Concat string parts	10715407.0 Ops/sec
Chained concat string parts	13509872.0 Ops/sec

Script Preparation code:

function joinPairJoin(separator, fst, snd) { return [fst, snd].join(separator) }
function joinPairConcat(separator, fst, snd) { return fst.concat(separator, snd) }
function joinPairConcatConcat(separator, fst, snd) { return fst.concat(separator).concat(snd) }
function joinPairAdd(separator, fst, snd) { return fst + separator + snd }

Tests:

Join string parts
const str = joinPairJoin('-', 'foo', 'bar')
Concat string parts
const str = joinPairConcat('-', 'foo', 'bar')
Chained concat string parts
const str = joinPairConcatConcat('-', 'foo', 'bar')
Add string parts
const str = joinPairAdd('-', 'foo', 'bar')

Run results for: arity 3 string join vs concat vs plus with separator

Join string parts

Concat string parts

Chained concat string parts

Add string parts