Run results for: querySelectorAll vs getElementsByClassName performance test for demo

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/104.0.0.0 Safari/537.36

Browser: Chrome 104

Operating system: Linux

Device Platform: Desktop

Date tested: 2 years ago

Test name	Executions per second
querySelectorAll	634243.8 Ops/sec
getElementsByClassName	2468501.8 Ops/sec

HTML Preparation code:

<ul>
        <li class="list">Text Element 1</li>
        <li class="list">Text Element 2</li>
        <li class="list">Text Element 3</li>
        <li class="list">Text Element 4</li>
        <li class="list">Text Element 5</li>
        <li class="list">Text Element 6</li>
        <li class="list">Text Element 7</li>
        <li class="list">Text Element 8</li>
        <li class="list">Text Element 9</li>
        <li class="list">Text Element 10</li>
        <li class="list">Text Element 11</li>
        <li class="list">Text Element 12</li>
        <li class="list">Text Element 13</li>
        <li class="list">Text Element 14</li>
        <li class="list">Text Element 15</li>
        <li class="list">Text Element 16</li>
        <li class="list">Text Element 17</li>
        <li class="list">Text Element 18</li>
        <li class="list">Text Element 19</li>
        <li class="list">Text Element 20</li>
    </ul>

Tests:

querySelectorAll
document.querySelectorAll('li');
getElementsByClassName
document.getElementsByClassName('list');

Run results for: querySelectorAll vs getElementsByClassName performance test for demo

Compare javascript selector performance

querySelectorAll

getElementsByClassName