Run results for: instanceof vs in options

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:138.0) Gecko/20100101 Firefox/138.0

Browser: Firefox 138

Operating system: Windows

Device Platform: Desktop

Date tested: one year ago

in test

1553.3M/s

proper type check

1387.4M/s

instanceof test again

160.1M/s

instanceof test

157.5M/s

includes check

45.1M/s

View exact numbers

Test name	Executions per second
✓ in test	1,553,290,624 Ops/sec
proper type check	1,387,363,968 Ops/sec
instanceof test again	160,112,240 Ops/sec
instanceof test	157,504,400 Ops/sec
includes check	45,093,188 Ops/sec

Script Preparation code:

class ClassFoo {
    constructor() {
        this.bar = 'classFoo';
    }
}

var knownTypes = ['otherClass', 'classFoo'];
var Foo = ClassFoo;
var foo = new Foo();

Tests:

instanceof test
foo instanceof Foo
in test
'bar' in foo
instanceof test again
foo instanceof Foo
proper type check
'bar' in foo && (foo.bar === 'otherClass' || foo.bar === 'classFoo')
includes check
'bar' in foo && knownTypes.includes(foo.bar)