Run results for: reduce: spreading acc vs mutating acc

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36

Browser: Chrome 131

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
spread acc	5387.6 Ops/sec
mutate acc	199174.9 Ops/sec

HTML Preparation code:

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

Script Preparation code:

function generateID(length = 10) {
    const characters = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
    let result = '';
    const charactersLength = characters.length;
    
    for (let i = 0; i < length; i++) {
        // Generate a random index based on characters length
        const randomIndex = Math.floor(Math.random() * charactersLength);
        // Append the character at the random index to the result string
        result += characters[randomIndex];
    }

    return result;
}

const data = new Array(100).fill('a').map(() => ({ key: generateID(), value: 'value' }));

Tests:

spread acc
const result = data.reduce((acc, item) => { return { ...acc, [item.key]: item.value, }; }, {});
mutate acc
const result = data.reduce((acc, item) => { acc[item.key] = item.value; return acc; }, {});

Run results for: reduce: spreading acc vs mutating acc

spread acc

mutate acc