Run results for: tagName vs instanceof

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Firefox/91.0

Browser: Firefox 91

Operating system: Linux

Device Platform: Desktop

Date tested: 2 years ago

Test name	Executions per second
instanceof	3681397.5 Ops/sec
tagName	4919854.5 Ops/sec
nodeName	5261308.0 Ops/sec
localName	5226043.0 Ops/sec
__proto__	6051002.5 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;

Run results for: tagName vs instanceof

instanceof

tagName

nodeName

localName

__proto__

proto