Run results for: for in vs object keys filter

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/97.0.4678.1 Safari/537.36

Browser: Chrome 97

Operating system: Windows

Device Platform: Desktop

Date tested: 2 years ago

Test name	Executions per second
For IN	14022.4 Ops/sec
Object Keys Filter	19793.8 Ops/sec

Script Preparation code:

var obj = {
    a: {
        isList: true
    },
    b: {
        isList: false
    },
    c: {
        isList: true
    },
    d: {
        isList: false
    },
    e: {
        isList: true
    },
    f: {
        isList: true
    }
};

Tests:

For IN
const arr = []; for (let prop in obj) { if (obj[prop].isList) { arr.push(prop); } } console.log(arr);
Object Keys Filter
const arr = Object.keys(obj).filter(prop => obj[prop].isList); console.log(arr);

Run results for: for in vs object keys filter

battle of the object key loops

For IN

Object Keys Filter