id vs class vs tag vs pseudo vs. attribute selectors

JavaScript performance comparison

Revision 17 of this test case created by Chris McKee

Info

Comparing the performance difference of varied jQuery 1.7 selectors. With a few little test of grabbing the same using the lovely DOM. The dom tests will have to live with the fact that jQuery has been loaded into the page.

This test page contains some dummy HTML (from html-ipsum.com) just to give the page some weight, make the selectors work a little bit.

Note that the "Tag" selector is selecting a tag that happens to be unique in the page just to be fair.

Preparation code

<style type="text/css">
  .bar { display: none; }
</style>
<div id="cheese">
  <h1>
    HTML Ipsum Presents
  </h1>
  <p>
    <strong>
      Pellentesque habitant morbi tristique
    </strong>
    senectus et netus et malesuada fames ac turpis egestas. Vestibulum tortor quam,
    feugiat vitae, ultricies eget, tempor sit amet, ante. Donec eu libero sit amet quam
    egestas semper.
    <em>
      Aenean ultricies mi vitae est.
    </em>
    Mauris placerat eleifend leo. Quisque sit amet est et sapien ullamcorper pharetra.
    Vestibulum erat wisi, condimentum sed,
    <code>
      commodo vitae
    </code>
    , ornare sit amet, wisi. Aenean fermentum, elit eget tincidunt condimentum, eros
    ipsum rutrum orci, sagittis tempus lacus enim ac dui.
    <a href="#">Donec non enim</a>
    in turpis pulvinar facilisis. Ut felis.
  </p>
  <h2>
    Header Level 2
  </h2>
  <ol>
    <li>
      Lorem ipsum dolor sit amet, consectetuer adipiscing elit.
    </li>
    <li>
      Aliquam tincidunt mauris eu risus.
    </li>
  </ol>
  <blockquote id="foo" class="bar" name="baz">
    <p>
      Lorem ipsum dolor sit amet, consectetur adipiscing elit. Vivamus magna. Cras in
      mi at felis aliquet congue. Ut a est eget ligula molestie gravida. Curabitur massa.
      Donec eleifend, libero at sagittis mollis, tellus est malesuada tellus, at luctus
      turpis elit sit amet quam. Vivamus pretium ornare est.
    </p>
  </blockquote>
  <h3>
    Header Level 3
  </h3>
  <ul>
    <li>
      Lorem ipsum dolor sit amet, consectetuer adipiscing elit.
    </li>
    <li>
      Aliquam tincidunt mauris eu risus.
    </li>
  </ul>
  <pre>
    <code>
      #header h1 a { display: block; width: 300px; height: 80px; }
    </code>
  </pre>
</div>
<script src="//ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js">
</script>

Preparation code output

HTML Ipsum Presents

Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Vestibulum tortor quam, feugiat vitae, ultricies eget, tempor sit amet, ante. Donec eu libero sit amet quam egestas semper. Aenean ultricies mi vitae est. Mauris placerat eleifend leo. Quisque sit amet est et sapien ullamcorper pharetra. Vestibulum erat wisi, condimentum sed, commodo vitae , ornare sit amet, wisi. Aenean fermentum, elit eget tincidunt condimentum, eros ipsum rutrum orci, sagittis tempus lacus enim ac dui. Donec non enim in turpis pulvinar facilisis. Ut felis.

Header Level 2

  1. Lorem ipsum dolor sit amet, consectetuer adipiscing elit.
  2. Aliquam tincidunt mauris eu risus.

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Vivamus magna. Cras in mi at felis aliquet congue. Ut a est eget ligula molestie gravida. Curabitur massa. Donec eleifend, libero at sagittis mollis, tellus est malesuada tellus, at luctus turpis elit sit amet quam. Vivamus pretium ornare est.

Header Level 3

  • Lorem ipsum dolor sit amet, consectetuer adipiscing elit.
  • Aliquam tincidunt mauris eu risus.
    
      #header h1 a { display: block; width: 300px; height: 80px; }
    
  

Test runner

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

Java applet disabled.

Testing in unknown unknown
Test Ops/sec
jQuery ID
$("#foo");
pending…
jQuery Tag
$("blockquote");
pending…
jQuery Class
$(".bar");
pending…
jQuery attribute
$("[name='baz']");
pending…
jQuery Pseudo-selector
$(":hidden");
pending…
DOM Get Element By Id
//$("#foo");
document.getElementById('foo');
pending…
DOM Get Element By Tag
document.getElementsByTagName('blockquote')
pending…
Get Elements by Class Name
/* Using an DustinDiaz function as fallback where getElementsByClassName isn't supported (ie 6/7 etc); this bit of testing for availability may have an adverse effect.*/

if (typeof document.getElementsByClassName !== 'function') {
  function getElementsByClass(searchClass, node, tag) {
    var classElements = new Array();
    if (node == null) node = document;
    if (tag == null) tag = '*';
    var els = node.getElementsByTagName(tag);
    var elsLen = els.length;
    var pattern = new RegExp("(^|\\s)" + searchClass + "(\\s|$)");
    for (i = 0, j = 0; i < elsLen; i++) {
      if (pattern.test(els[i].className)) {
        classElements[j] = els[i];
        j++;
      }
    }
    return classElements;
  }
}

document.getElementsByClassName('bar')
pending…
Get Element By Name Attribute
// document.getElementsByName() is in the HTML5 spec but is pretty damn old; returns HTML Collection of elements
document.getElementsByName('baz')
pending…
Get Element By Attribute
/* Last one felt like a cop out, but the test is crap choice of showing the power of the pseudo selectors/attribute selectors in jQuery so this is a more 'generic' method for attributes.
I literally just smashed this out so forgive me ><
*/


function getElementsByAttribute(strAttText, strAttType) {
  var aEle = [],
      node = document,
      tag = '*',
      i = 0,
      j = 0;
  var els = node.getElementsByTagName(tag);
  var pattern = new RegExp("(^|\\s)" + strAttText + "(\\s|$)");
  for (; i < els.length; i++) {
    if (pattern.test(els[i].getAttribute(strAttType))) {
      aEle[j] = els[i];
      j++;
    }
  }
  return aEle;
}

getElementsByAttribute('baz', 'name');
pending…
jQuery Element limited scope
$("#cheese").find("p");
pending…
jQuery Element limited scope another way
$("#cheese", "p");
pending…
DOM Element limited scope
var ele = document.getElementById("cheese"),
    header = ele.getElementsByTagName("p");
pending…
Alt-Pseudo Selector (uses dom function/regex etc)
/* You only get to play with document.querySelectorAll in IE8+ (and browsers worth caring about) but...

document.querySelectorAll(":hidden"); Wont work, its not supposed to.
As with most things DOM, if its written in C it should be faster; but hidden is special and theres a valid reason why it wont be caught (read the links below).

https://developer.mozilla.org/En/DOM/Document.querySelectorAll

Reading for those who give a crap.
* http://www.w3.org/TR/css3-selectors/#UIstates
* https://bugzilla.mozilla.org/show_bug.cgi?id=410472
----
This Test instead uses a method created in 2005 :D
*/


/* stuff of dreams many years ago.
http://dean.edwards.name/my/cssQuery/
*/

/*
        cssQuery, version 2.0.2 (2005-08-19)
        Copyright: 2004-2005, Dean Edwards (http://dean.edwards.name/)
        License: http://creativecommons.org/licenses/LGPL/2.1/
*/

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x}();',62,190,'|||||return|function|var|if|for||||||||pseudoClasses||||test|||this||AttributeSelector|||||||cssQuery|length|push|fr|id||selectors||case|nextElementSibling|while||tests|true|false|thisElement||replace|match|getDocument|regEscape||attributeSelectors|isMSIE|cache||getElementsByTagName|isNaN|slice|child||new|getAttribute|compareNamespace|addModule|previousElementSibling|compareTagName|parseSelector|loaded|break|_0|nodeType|switch|getTextContent|tagName|document|isXML|eval|css|_1|split|ch|parentNode|childElements|nthChild|disabled|firstElementChild|getText|RegExp|Quote|x22|PREFIX|lang|_2|arguments|else|all|links|version|se|childNodes|innerText|documentElement|contentType|xml|parseInt|indeterminate|checked|last|nth|lastElementChild|parse|_3|add|href|String|className|create|NS_IE|remove|toString|ST|select|Array|null|_4|mimeType|lastChild|firstChild|continue|modules|delete|join|caching|error|nodeValue|textContent|HTML|prefix|getElementsByTagNameNS|end|x5fwin32|cc_on|standard||odd|even|enabled|hash|location|target|not|only|empty|root|contains|level3|outerHTML|htmlFor|class|toLowerCase|Function|name|first|level2|prototype|item|scopeName|toUpperCase|ownerDocument|Document|XML|Boolean|URL|unknown|typeof|nextSibling|previousSibling|visited|link|valueOf|clearCache|catch|concat|constructor|callee|try'.split('|'),0,{}))


cssQuery(":hidden");
pending…

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