Run results for: $.hasClass vs RegExp vs indexOf vs classList

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.66 Safari/537.36

Browser: Chrome 87

Operating system: Windows

Device Platform: Desktop

Date tested: 3 years ago

Test name	Executions per second
$.hasClass	506538.8 Ops/sec
RegExp	723947.7 Ops/sec
Dry RegExp	348754.1 Ops/sec
indexOf	1679394.6 Ops/sec
classList	1998981.9 Ops/sec
hasClassString	1002785.7 Ops/sec
RegExp 2	1199511.9 Ops/sec
RegExp 3	871022.4 Ops/sec
RegExp 4	1015889.2 Ops/sec
RegExp 5	1092445.0 Ops/sec
indexOf simplest	3336766.8 Ops/sec

HTML Preparation code:

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js"></script>

<div class="foobar" id="node">Hello</div>

Script Preparation code:

var node = document.getElementById('node');
var $node = $(node);
var rx = new RegExp('\\bfoobar\\b');
var rx2 = new RegExp('(^| )foobar( |$)', 'gi');
var rx3 = new RegExp('(^| )foobar( |$)');
var rx4 = new RegExp('(^| )foobar( |$)', 'g');
var rx5 = new RegExp('(^| )foobar( |$)', 'i');
function hasClassString(e, c) {
  var s = e.className, i = s.indexOf(c);
  return i != -1 && (s.charCodeAt(i - 1) || 32) == 32 && (s.charCodeAt(i + c.length) || 32) == 32;
};

Tests:

$.hasClass
var hasClass = $node.hasClass('foobar');
RegExp
var hasClass = rx.test(node.className);
Dry RegExp
var drx = new RegExp('\\bfoobar\\b'); var hasClass = drx.test(node.className);
indexOf
var hasClass = (" " + node.className + " ").indexOf(" foobar ") !== -1;
classList
var hasClass = node.classList.contains('foobar');
hasClassString
var hasClass = hasClassString(node, 'foobar');
RegExp 2
var hasClass = rx2.test(node.className)
RegExp 3
var hasClass = rx3.test(node.className)
RegExp 4
var hasClass = rx4.test(node.className)
RegExp 5
var hasClass = rx4.test(node.className)
indexOf simplest
var hasClass = (node.className).indexOf("foobar") !== -1;

Run results for: $.hasClass vs RegExp vs indexOf vs classList

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$.hasClass

RegExp

Dry RegExp

indexOf

classList

hasClassString

RegExp 2

RegExp 3

RegExp 4

RegExp 5

indexOf simplest