getElementById vs getElementsByClassName (v27)

Revision 27 of this benchmark created by mingodad on

Preparation HTML

<div class="class1" id="id1"></div>
<div class="class2" id="id2"></div>
<div class="class3" id="id3"></div>
<div class="class4" id="id4"></div>
<div class="class5" id="id5"></div>
<div class="class6" id="id6"></div>
<div class="class7" id="id7"></div>
<div class="class8" id="id8"></div>
<div class="class9" id="id9"></div>
<div class="class10" id="id10"></div>

<div class="class11" id="id11"></div>
<div class="class12" id="id12"></div>
<div class="class13" id="id13"></div>
<div class="class14" id="id14"></div>
<div class="class15" id="id15"></div>
<div class="class16" id="id16"></div>
<div class="class17" id="id17"></div>
<div class="class18" id="id18"></div>
<div class="class19" id="id19"></div>
<div class="class20" id="id20"></div>


<div class="class21" id="id21"></div>
<div class="class22" id="id22"></div>
<div class="class23" id="id23"></div>
<div class="class24" id="id24"></div>
<div class="class25" id="id25"></div>
<div class="class26" id="id26"></div>
<div class="class27" id="id27"></div>
<div class="class28" id="id28"></div>
<div class="class29" id="id29"></div>
<div class="class30" id="id30"></div>

Test runner

Ready to run.

Testing in
TestOps/sec
getElementById
for (var i = 1; i <= 30; i++) {
  var x = document.getElementById("id" + i);
};
ready
getElementsByClassName
for (var i = 1; i <= 30; i++) {
  var x = document.getElementsByClassName("class" + i)[0];
};
ready
for loop over all dom
var theChildren = document.body.children;
var clen = theChildren.length;
for (var i = 1; i <= 30; i++) {
  var theClass = "class" + i;
  for(var j=0; j < clen; j++)
  {
    if(theChildren[j].className === theClass)
    {
       var x = theChildren[j];
       break;
    }
  }
};
ready

Revisions

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