Run results for: instanceof vs manual checking

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/133.0.0.0 Safari/537.36

Browser: Chrome 133

Operating system: Windows

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
base instanceof Base	113808528.0 Ops/sec
extender instanceof Base	115179872.0 Ops/sec
base instanceof Extender	118679016.0 Ops/sec
extender instanceof Extender	127838376.0 Ops/sec
objBase check property	123774040.0 Ops/sec
objExtender check property	113899272.0 Ops/sec

Script Preparation code:

class Base {
   constructor() {
     this.a = 123; 
   }
  
   doSomething() {
     console.log(this.a); 
   }
}

class Extender extends Base {
 	constructor() {
      super();
      this.b = 345;
    }
}

const objBase = new Base();
const objExt = new Extender();

Tests:

base instanceof Base
objBase instanceof Base
extender instanceof Base
objExt instanceof Base
base instanceof Extender
objBase instanceof Extender
extender instanceof Extender
objExt instanceof Extender
objBase check property
!!objBase.b
objExtender check property
!!objExt.b

Run results for: instanceof vs manual checking

Determining if instanceof is slower than checking against a known property

base instanceof Base

extender instanceof Base

base instanceof Extender

extender instanceof Extender

objBase check property

objExtender check property