Run results for: tagName vs instanceof

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_16_0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/86.0.4204.0 Safari/537.36

Browser: Chrome 86

Operating system: Mac OS X 10.16.0

Device Platform: Desktop

Date tested: 4 years ago

Test name	Executions per second
instanceof	1695211.2 Ops/sec
tagName	2324902.0 Ops/sec
nodeName	2289910.5 Ops/sec
localName	2329193.8 Ops/sec
__proto__	1818860.8 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