object-instantiation-performance.js

function createBencher(iters) {
    return function runBench(label, fn) {
        console.time(label);
        
        for (let i = 0; i < iters; i++) {
            fn();
        }
        
        console.timeEnd(label);
    }
}

class Assigner {
    constructor(props) {
        Object.assign(this, props);
    }
}

class AssignerForIn {
    constructor(props) {
        for (let key in props) {
            this[key] = props[key];
        }
    }
}

class DirectAssigner_4props {
    constructor(props) {
        this.name = props.name;
        this.color = props.color;
        this.age = props.age;
        this.city = props.city;
    }
}

class DirectAssigner_8props {
    constructor(props) {
        this.name = props.name;
        this.color = props.color;
        this.age = props.age;
        this.city = props.city;
        this.favorite_color = props.favorite_color;
        this.favorite_food = props.favorite_food;
        this.favorite_animal = props.favorite_animal;
        this.favorite_sport = props.favorite_sport;
    }
}

class DirectAssigner_12props {
    constructor(props) {
        this.name = props.name;
        this.color = props.color;
        this.age = props.age;
        this.city = props.city;
        this.favorite_color = props.favorite_color;
        this.favorite_food = props.favorite_food;
        this.favorite_animal = props.favorite_animal;
        this.favorite_sport = props.favorite_sport;
        this.birth_date = props.birth_date;
        this.birth_country = props.birth_country;
        this.birth_state = props.birth_state;
        this.birth_city = props.birth_city;
    }
}

const obj_4props = {
    name: 'John',
    color: 'blue',
    age: 25,
    city: 'New York',
};
const obj_8props = {
    name: 'John',
    color: 'blue',
    age: 25,
    city: 'New York',
    favorite_color: 'red',
    favorite_food: 'pizza',
    favorite_animal: 'dog',
    favorite_sport: 'soccer',
};
const obj_12props = {
    name: 'John',
    color: 'blue',
    age: 25,
    city: 'New York',
    favorite_color: 'red',
    favorite_food: 'pizza',
    favorite_animal: 'dog',
    favorite_sport: 'soccer',
    birth_date: '01/01/1995',
    birth_country: 'USA',
    birth_state: 'California',
    birth_city: 'Los Angeles',
};
const runBench = createBencher(1e6);

runBench('Object.assign with 4 properties', () => new Assigner(obj_4props));
runBench('Object.assign with 8 properties', () => new Assigner(obj_8props));
runBench('Object.assign with 12 properties', () => new Assigner(obj_12props));

runBench('For in with 4 properties', () => new AssignerForIn(obj_4props));
runBench('For in with 8 properties', () => new AssignerForIn(obj_8props));
runBench('For in with 12 properties', () => new AssignerForIn(obj_12props));

runBench('Direct assignment with 4 properties', () => new DirectAssigner_4props(obj_4props));
runBench('Direct assignment with 8 properties', () => new DirectAssigner_8props(obj_8props));
runBench('Direct assignment with 12 properties', () => new DirectAssigner_12props(obj_12props));

// Object.assign with 4 properties: 46.676ms
// Object.assign with 8 properties: 93.73ms
// Object.assign with 12 properties: 148.207ms
// For in with 4 properties: 52.75ms
// For in with 8 properties: 115.907ms
// For in with 12 properties: 184.789ms
// Direct assignment with 4 properties: 7.567ms
// Direct assignment with 8 properties: 12.467ms
// Direct assignment with 12 properties: 11.392ms