Run results for: tagName vs instanceof

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:139.0) Gecko/20100101 Firefox/139.0

Browser: Firefox 139

Operating system: Windows

Device Platform: Desktop

Date tested: one year ago

instanceof

38.3M/s

localName

34.2M/s

__proto__

34.0M/s

nodeName

33.4M/s

tagName

27.1M/s

View exact numbers

Test name	Executions per second
✓ instanceof	38,288,080 Ops/sec
localName	34,239,392 Ops/sec
__proto__	33,995,020 Ops/sec
nodeName	33,436,738 Ops/sec
tagName	27,111,902 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
n += (xs[(Math.random() * 1000)|0].tagName === `DIV`)|0;
nodeName
n += (xs[(Math.random() * 1000)|0].nodeName === `DIV`)|0;
localName
n += (xs[(Math.random() * 1000)|0].localName === `div`)|0;
__proto__
n += ((xs[(Math.random() * 1000)|0]).__proto__ === HTMLDivElement.prototype)|0;