className VS classList Showdown

Benchmark created by Jason Miller on

Description

How much faster is classList.add/remove than className regex manipulation?

Preparation HTML

<style type="text/css">
.foo { color:#F00; height:100px; opacity:0.3; }
.bar { color:#0F0; height:200px; opacity:0.5; }
.baz { color:#00F; height:300px; opacity:0.7; }
</style>

<div id="base" class="foo bar">
  <div class="foo bar baz">test 1</div>
  <span class="foo bar">test 2</span>
  <span class="baz">test 3</span>
</div>

Setup

var node = document.getElementById('base'),
        className = 'baz';
    
    function addClass_className(el, className) {
        var cn = el.className || '',
            c = ' '+cn+' ',
            p = ' '+className+' ';
        if (c.indexOf(p)===-1) {
            el.className = cn + (cn ? ' ' : '') + className;
        }
    }
    
    
    function removeClass_className(el, className) {
        var cn = el.className || '',
            c = ' '+cn+' ',
            p = ' '+className+' ';
        if (c.indexOf(p)!==-1) {
            c = c.replace(p,' ');
            el.className = c.substring(1, c.length-2);
        }
    }
    
    function addClass_classList(el, className) {
        el.classList.add(className);
    }
    
    function removeClass_classList(el, className) {
        el.classList.remove(className);
    }

Test runner

Ready to run.

Testing in
TestOps/sec
className RegExp
addClass_className(node, className);
addClass_className(node, className);
removeClass_className(node, className);
removeClass_className(node, className);
 
ready
classList
addClass_classList(node, className);
addClass_classList(node, className);
removeClass_classList(node, className);
removeClass_classList(node, className);
 
ready

Revisions

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