Access to nodes via querySelectorAll vs getElementsByTagName

JavaScript performance comparison

Revision 2 of this test case created


we discovered that calling getelementsbytagname('DIV') is a way faster than queryselectorall('DIV')

the reason being that the former returns an HTMLCollection (live list) and the later a NodeList (static list). To go further we will see if accessing properties of a static list compensates the time to create it

Preparation code

    <li><a href="#">item 1</a></li>
    <li><a href="#">item 2</a></li>
    <li><a href="#">item 3</a></li>
    <li><a href="#">item 4</a></li>
    <li><a href="#">item 5</a></li>
    <li><a href="#">item 6</a></li>
    <li><a href="#">item 7</a></li>
    <li><a href="#">item 8</a></li>
    <li><a href="#">item 9</a></li>
    <li><a href="#">item 10</a></li>
    <li><a href="#">item 11</a></li>
    <li><a href="#">item 12</a></li>
    <li><a href="#">item 13</a></li>
    <li><a href="#">item 14</a></li>
    <li><a href="#">item 15</a></li>
    <li><a href="#">item 16</a></li>
    <li><a href="#">item 17</a></li>

Preparation code output

Test runner

Warning! For accurate results, please disable Firebug before running the tests. (Why?)

Java applet disabled.

Testing in unknown unknown
Test Ops/sec
var nodes = document.querySelectorAll('a');
var href;
for (var i = 0, iLength = nodes.length; i < iLength; i++) {
 href = nodes[i].href;
 nodes[i].href = 'another url';
var nodes = document.getElementsByTagName('a');
for (var i = 0, iLength = nodes.length; i < iLength; i++) {
 href = nodes[i].href;
 nodes[i].href = 'another url';

Compare results of other browsers


You can edit these tests or add even more tests to this page by appending /edit to the URL. Here’s a list of current revisions for this page:


Comment form temporarily disabled.

Add a comment