Run results for: JS lastIndexOf vs indexOf

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36

Browser: Chrome 131

Operating system: Windows

Device Platform: Desktop

Date tested: one year ago

Array.lastIndexOf

10.8M/s

Array.indexOf

2K/s

View exact numbers

Test name	Executions per second
✓ Array.lastIndexOf	10,767,309 Ops/sec
Array.indexOf	2,088 Ops/sec

Script Preparation code:

var str = '';
var i = 0;

while (i <= 1E5) str += `${i++}`;

Tests: