Run results for: tagName.toLowerCase() vs instanceof

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/136.0.0.0 Safari/537.36

Browser: Chrome 136

Operating system: Linux

Device Platform: Desktop

Date tested: one year ago

__proto__

16.3M/s

instanceof

13.8M/s

localName

12.2M/s

nodeName.toLowerCase()

11.5M/s

tagName.toLowerCase()

11.4M/s

View exact numbers

Test name	Executions per second
✓ __proto__	16,341,625 Ops/sec
instanceof	13,798,491 Ops/sec
localName	12,162,344 Ops/sec
nodeName.toLowerCase()	11,491,501 Ops/sec
tagName.toLowerCase()	11,444,052 Ops/sec

Script Preparation code:

var xs = [];
var n = 0;

for (let i = 0; i < 1000; ++i) {
  xs[i] = (Math.random() > .5) ? document.createElement(`div`) : document.createElement(`span`);
};

Tests:

instanceof
n += ((xs[(Math.random() * 1000)|0]) instanceof HTMLDivElement)|0;
tagName.toLowerCase()
n += (xs[(Math.random() * 1000)|0].tagName.toLowerCase() === `div`)|0;
nodeName.toLowerCase()
n += (xs[(Math.random() * 1000)|0].nodeName.toLowerCase() === `div`)|0;
localName
n += (xs[(Math.random() * 1000)|0].localName === `div`)|0;
__proto__
n += ((xs[(Math.random() * 1000)|0]).__proto__ === HTMLDivElement.prototype)|0;