Run results for: tagName vs instanceof

Run details:

User agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:123.0) Gecko/20100101 Firefox/123.0

Browser: Firefox 123

Operating system: Ubuntu

Device Platform: Desktop

Date tested: 2 years ago

__proto__

12.6M/s

nodeName

11.7M/s

localName

10.9M/s

tagName

10.7M/s

instanceof

5.7M/s

View exact numbers

Test name	Executions per second
✓ __proto__	12,635,230 Ops/sec
nodeName	11,723,603 Ops/sec
localName	10,918,026 Ops/sec
tagName	10,679,078 Ops/sec
instanceof	5,693,664 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;