Run results for: Monomorphic vs Typed Monomorphic vs Empty Object prop assignment

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/15.4 Safari/605.1.15

Browser: Safari 15

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 2 years ago

Test name	Executions per second
Monomorphic	21568.0 Ops/sec
Monomorphic Typed	21506.0 Ops/sec
Empty Object	23635.0 Ops/sec

Script Preparation code:

const source = {
    a: "",
    b: "",
    c: "",
    setA: function() {
        this.a = "";
    },
    setB: function() {
        this.b = "";
    },
    setC: function() {
        this.c = "";
    },
};

function assignProps1(target) {
    for (const key in source) {
        target[key] = source[key];
    }
};
function assignProps2(target) {
    for (const key in source) {
        target[key] = source[key];
    }
};
function assignProps3(target) {
    for (const key in source) {
        target[key] = source[key];
    }
};


const noop = function() {};

function getMonoData() {
    return {
        a: null,
        b: null,
        c: null,
        setA: null,
        setB: null,
        setC: null
    };
}

function getTypedData() {
    return {
        a: "",
        b: "",
        c: "",
        setA: noop,
        setB: noop,
        setC: noop
    };
}

function getEmptyData() {
    return {};
}

Tests:

Monomorphic
assignProps1(getMonoData());
Monomorphic Typed
assignProps2(getTypedData());
Empty Object
assignProps3(getEmptyData());

Run results for: Monomorphic vs Typed Monomorphic vs Empty Object prop assignment

Monomorphic

Monomorphic Typed

Empty Object