Run results for: querySelector vs querySelectorAll vs getElementsByClassName vs querySelector (ID) vs getElementsByID - MeasureThat.net

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:48.0) Gecko/20100101 Firefox/48.0

Browser: Firefox 48

Operating system: Mac OS X 10.8

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
querySelector	2104524.0 Ops/sec
querySelectorAll	495433.3 Ops/sec
getElementsByClassName	18938000.0 Ops/sec
querySelector (ID)	2219702.0 Ops/sec
getElementsByID	18952610.0 Ops/sec

Website performance monitoring

HTML Preparation code:

<div class="test" id="test"></div>

Tests:

querySelector
document.querySelector(".test")
querySelectorAll
document.querySelectorAll(".test")
getElementsByClassName
document.getElementsByClassName(".test")
querySelector (ID)
document.querySelector("#test")
getElementsByID
document.getElementById("test")