Benchmark: .concat() is slow (immutable) vs .push() (mutation)

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

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
spread
assign key

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

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/OS: Chrome 131 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
spread	5190.5 Ops/sec
assign key	207778.0 Ops/sec

Related benchmarks:

.concat() is slow (immutable) vs .push() (mutation) (version: 1)

Comparing performance of: spread vs assign key

Created: one year ago by: Guest

Jump to the latest result

spread

assign key

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A