Run results for: JS array lastIndexOf vs indexOf

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:147.0) Gecko/20100101 Firefox/147.0

Browser: Firefox 147

Operating system: Windows

Device Platform: Desktop

Date tested: 2 months ago

Test name	Executions per second
Array.lastIndexOf	188291.7 Ops/sec
Array.indexOf	128192.9 Ops/sec

Script Preparation code:

var a = [];
var i = 0;

while (i <= 1E5) {
  i++;
  // Put the two results same disance from start and end
  if(i === 1E5 - 1E4 || i === 1E4) str.push("match")
  else a.push(i)
}

Tests:

Array.lastIndexOf
const item = a.lastIndexOf("match");
Array.indexOf
const index = a.indexOf("match");

Run results for: JS array lastIndexOf vs indexOf

JS array lastIndexOf vs indexOf

Array.lastIndexOf

Array.indexOf