Run results for: Different types of selecting

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3578.98 Safari/537.36

Browser: Chrome 71

Operating system: Windows

Device Platform: Desktop

Date tested: 5 years ago

Test name	Executions per second
getElementById	2502217.0 Ops/sec
querySelector("#id")	1222901.0 Ops/sec
getElementsByClassName("class")[0]	1668651.0 Ops/sec
querySelector(".class")	1691051.0 Ops/sec
getElementById + getElementsByTagName	1916785.0 Ops/sec
querySelectorAll("#id tag")	410070.6 Ops/sec
getElementById + getElementsByClassName[0]	1578811.0 Ops/sec
querySelector("#id .class")	1605944.0 Ops/sec
getElementsByClassName("class")	3414413.0 Ops/sec
querySelectorAll(".class")	790247.0 Ops/sec

HTML Preparation code:

<div>
  <ul id="id1">
    <li class="c1">Element</li>
    <li id="id2" class="c1">Element</li>
    <li class="c1">Element</li>
    <li class="c1">Element</li>
  </ul>
</div>

Tests:

getElementById
document.getElementById("id2")
querySelector("#id")
document.querySelector("#id2")
getElementsByClassName("class")[0]
document.getElementsByClassName("c1")[0]
querySelector(".class")
document.querySelector(".c1")
getElementById + getElementsByTagName
document.getElementById("id1").getElementsByTagName("li")
querySelectorAll("#id tag")
document.querySelectorAll("#id1 li")
getElementById + getElementsByClassName[0]
document.getElementById("id1").getElementsByClassName("c1")[0]
querySelector("#id .class")
document.querySelector("#id1 .c1")
getElementsByClassName("class")
document.getElementsByClassName("c1")
querySelectorAll(".class")
document.querySelectorAll(".c1")

Run results for: Different types of selecting

getElementById

querySelector("#id")

getElementsByClassName("class")[0]

querySelector(".class")

getElementById + getElementsByTagName

querySelectorAll("#id tag")

getElementById + getElementsByClassName[0]

querySelector("#id .class")

getElementsByClassName("class")

querySelectorAll(".class")