Run results for: index vs lastindexof (for right biased values) - MeasureThat.net

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_6) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/15.1 Safari/605.1.15

Browser: Safari 15

Operating system: Mac OS X 10.15.6

Device Platform: Desktop

Date tested: 2 years ago

Test name	Executions per second
lastIndexOf (near end)	2531560.0 Ops/sec
indexOf (near end)	87787.9 Ops/sec
lastIndexOf (near head)	100053.9 Ops/sec
indexOf (near head)	1508575.0 Ops/sec

Script Preparation code:

var a = [...Array(20000)].map((x, i) => i);
var i = 0;

Tests:

lastIndexOf (near end)
var n = a.lastIndexOf(19000 + (i++ % 1000));
indexOf (near end)
var n = a.indexOf(19000 + (i++ % 1000));
lastIndexOf (near head)
var n = a.lastIndexOf(0 + (i++ % 1000));
indexOf (near head)
var n = a.indexOf(0 + (i++ % 1000));