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

conditionally trim and conditionally replace

3K/s

trim and conditionally replace with if

3K/s

trim and conditionally replace

3K/s

trim and always replace

2K/s

always replace and trim

2K/s

View exact numbers

Test name	Executions per second
✓ conditionally trim and conditionally replace	2,641 Ops/sec
trim and conditionally replace with if	2,608 Ops/sec
trim and conditionally replace	2,605 Ops/sec
trim and always replace	2,454 Ops/sec
always replace and trim	2,256 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, ' '); } })