Run results for: Instanceof vs string comparison vs property checking vs constructor comparison

Run details:

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 16_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) CriOS/107.0.5304.101 Mobile/15E148 Safari/604.1

Browser: Chrome Mobile iOS 107

Operating system: iOS 16.1

Device Platform: Mobile

Date tested: 2 years ago

Test name	Executions per second
instanceof	9180176.0 Ops/sec
string type	22198644.0 Ops/sec
string type + undefined	7454887.5 Ops/sec
property	7470877.0 Ops/sec
constructor comparison	8852080.0 Ops/sec

HTML Preparation code:

<script>
class TestClass {
    constructor() {
        this.a = 2;
        this.t = 'mesh';
    }
}
</script>

Script Preparation code:

var obj = new TestClass();

Tests:

instanceof
obj instanceof TestClass;
string type
obj.t === 'mesh'
string type + undefined
obj.t !== undefined
property
obj.a !== undefined
constructor comparison
obj.constructor === TestClass

Run results for: Instanceof vs string comparison vs property checking vs constructor comparison

Measure the performance of instanceOf operator vs comparing a basic string type.

instanceof

string type

string type + undefined

property

constructor comparison