Run results for: Is it worth checking for empty string before replace with regex?

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:136.0) Gecko/20100101 Firefox/136.0

Browser: Firefox 136

Operating system: Mac OS X 10.15

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
trim and always replace	2453.7 Ops/sec
trim and conditionally replace	2604.8 Ops/sec
trim and conditionally replace with if	2607.7 Ops/sec
always replace and trim	2255.7 Ops/sec
conditionally trim and conditionally replace	2641.4 Ops/sec

Script Preparation code:

const arr = []
for(let i = 1; i < 1000; i++) {
    arr.push(' '.repeat(i))
}
for(let i = 1; i < 100; i++) {
    arr.push('');
    arr.push(' text '.repeat(i))
}

const run = (fn) => {
    const result = []
    for(const val of arr) {
        result.push(fn(val));
    }
    return result
}

Tests:

trim and always replace
run((val) => val.trim().replace(/\s+/g, ' '))
trim and conditionally replace
run((val) => { const trimmed = val.trim(); return trimmed && trimmed.replace(/\s+/g, ' '); })
trim and conditionally replace with if
run((val) => { const trimmed = val.trim(); if (trimmed === '') { return ''; } else { return trimmed.replace(/\s+/g, ' '); } })
always replace and trim
run((val) => val.replace(/\s+/g, ' ').trim())
conditionally trim and conditionally replace
run((val) => { if(val === '') { return val; } const trimmed = val.trim(); if (trimmed === '') { return trimmed; } else { return trimmed.replace(/\s+/g, ' '); } })

Run results for: Is it worth checking for empty string before replace with regex?

trim and always replace

trim and conditionally replace

trim and conditionally replace with if

always replace and trim

conditionally trim and conditionally replace