Benchmark: JS string split fix Len

HTML Preparation code:

<!--your preparation HTML code goes here-->

Script Preparation code:

let chars = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';
let parts = [];
for (let i = 0; i < 1000; i++) {
  const len = Math.floor(Math.random() * 200) + 1;
  let str = '';
  for (let j = 0; j < len; j++) {
    str += chars[Math.floor(Math.random() * chars.length)];
  }
  parts.push(str);
}
const testData = parts.join(',');

 chars = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';
 parts = [];
for (let i = 0; i < 1000; i++) {
  const subparts = [];
  const numSubparts = Math.floor(Math.random() * 5) + 1;
  
  for (let j = 0; j < numSubparts; j++) {
    const len = Math.floor(Math.random() * 100) + 1;
    let str = '';
    for (let k = 0; k < len; k++) {
      str += chars[Math.floor(Math.random() * chars.length)];
    }
    subparts.push(str);
  }
  
  parts.push(subparts.join(';'));
}
const testData2 = parts.join(',');

Tests:

regex
testData2.split(',').map(p => p.split(';'))
Slice
testData.split(',').map(p => { const r = []; for (let i = 0; i < p.length; i += 12) r.push(p.slice(i, i + 12)); return r; })
Prealloc slice
testData.split(',').map(p => { const r = new Array(Math.ceil(p.length / 12)); for (let i = 0, j = 0; i < p.length; i += 12, j++) { r[j] = p.slice(i, i + 12); } return r; })
Substr
testData.split(',').map(p => { const r = []; for (let i = 0; i < p.length; i += 12) r.push(p.substring(i, i + 12)); return r; })
Loop
testData.split(',').map(p => { const r = []; let i = 0; while (i < p.length) { r.push(p.slice(i, i += 12)); } return r; })

Historical Performance Data aggregated from 5 community runs

Mobile Results:

Chrome 5 runs

regex

8K/s

Prealloc slice

7K/s

Substr

7K/s

Slice

7K/s

Loop

7K/s

Fastest: regex (1.2x faster)

View exact numbers

✓ regex: 8,431 ops/sec
• Prealloc slice: 7,370 ops/sec
• Substr : 7,055 ops/sec
• Slice: 7,006 ops/sec
• Loop: 6,795 ops/sec

Results show median performance across all community submissions. Run this benchmark yourself to verify on your device.

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
regex
Slice
Prealloc slice
Substr
Loop

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 18_6 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) CriOS/129.0.6668.69 Mobile/15E148 Safari/604.1

Browser/OS: Chrome Mobile iOS 129 on iOS 18.6

View result in a separate tab

regex

9K/s

Prealloc slice

7K/s

Substr

7K/s

Slice

7K/s

Loop

7K/s

View exact numbers

Test name	Executions per second
✓ regex	8,664 Ops/sec
Prealloc slice	7,148 Ops/sec
Substr	6,983 Ops/sec
Slice	6,781 Ops/sec
Loop	6,501 Ops/sec

JS string split fix Len (version: 4)

Comparing performance of: `regex vs Slice vs Prealloc slice vs Substr vs Loop`

Created: one year ago by: Registered User

Go to the latest result

regex

Slice

Prealloc slice

Substr

Loop

Historical Performance Data aggregated from 5 community runs

Mobile Results:

Chrome 5 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

JS string split fix Len (version: 4)

Comparing performance of: regex vs Slice vs Prealloc slice vs Substr vs Loop

Created: one year ago by: Registered User

Go to the latest result

regex

Slice

Prealloc slice

Substr

Loop

Historical Performance Data aggregated from 5 community runs

Mobile Results:

Chrome 5 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Related benchmarks

Comparing performance of: `regex vs Slice vs Prealloc slice vs Substr vs Loop`