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

Run details:

User agent: Mozilla/5.0 (iPad; CPU OS 18_1_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) CriOS/132.0.6834.100 Mobile/15E148 Safari/604.1

Browser: Chrome Mobile iOS 132

Operating system: iOS 18.1.1

Device Platform: Tablet

Date tested: one year ago

Benchmark engine: Benchmark.js

Monomorphic

35.4M/s

Monomorphic Typed

34.7M/s

Empty Object

19.4M/s

View exact numbers

Test name	Executions per second
✓ Monomorphic	35,398,024 Ops/sec
Monomorphic Typed	34,668,316 Ops/sec
Empty Object	19,402,314 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());