Run results for: Reading from objects - Frozen vs Unfrozen

This compares the speed of accessing properties from a frozen object versus an unfrozen object. The example uses a simulated struct but one reason someone may use a frozen object is to use it like an enum and lock the amount of valid values.

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/26.2 Safari/605.1.15

Browser: Safari 26

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 7 months ago

Frozen

17K/s

Unfrozen

17K/s

View exact numbers

Test name	Executions per second
✓ Frozen	17,168 Ops/sec
Unfrozen	17,036 Ops/sec

HTML Preparation code:

<!--your preparation HTML code goes here-->

Script Preparation code:

function new_struct() {
    return {
        a: Math.random(),
        b: Math.random(),
        c: Math.random(),
        d: Math.random(),
    };
}

var structs1 = new Array(10000);
var structs2 = new Array(10000);

var new_values = new Array(10000);
var results = new Array(10000);

for (let i = 0; i < 10000; i++) {
    structs1[i] = new_struct();
    structs2[i] = Object.freeze(
        Object.assign(new_struct(), structs1[i])
    );
    results[i] = new_struct();
    new_values[i] = new_struct();
}

Tests:

Frozen
for (let i = 0; i < results.length; i++) { results[i].a = structs1[i].a + new_values[i].a; results[i].b = structs1[i].b + new_values[i].b; results[i].c = structs1[i].c + new_values[i].c; results[i].d = structs1[i].d + new_values[i].d; }
Unfrozen
for (let i = 0; i < results.length; i++) { results[i].a = structs2[i].a + new_values[i].a; results[i].b = structs2[i].b + new_values[i].b; results[i].c = structs2[i].c + new_values[i].c; results[i].d = structs2[i].d + new_values[i].d; }