Run results for: tagName vs instanceof

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/135.0.0.0 Safari/537.36

Browser: Chrome 135

Operating system: Windows

Device Platform: Desktop

Date tested: one year ago

__proto__

8.6M/s

instanceof

7.5M/s

localName

6.6M/s

tagName

6.4M/s

nodeName

6.3M/s

View exact numbers

Test name	Executions per second
✓ __proto__	8,552,867 Ops/sec
instanceof	7,464,936 Ops/sec
localName	6,576,628 Ops/sec
tagName	6,362,516 Ops/sec
nodeName	6,286,314 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;