Benchmark: cached Number.toLocaleString vs Intl.NumberFormat

HTML Preparation code:

<script>
    function toLocaleString(number = NaN, decimals) {
        return number.toLocaleString('en-US', {
            maximumFractionDigits: decimals,
            minimumFractionDigits: decimals,
        });
    };

    const numberFormatter = new Intl.NumberFormat('en-US');
    const formatCache = new Map();

    function formatNumber(number = NaN, decimals) {
        // Handle NaN early to avoid unnecessary processing
        if (isNaN(number)) {
            return 'NaN';
        }

        // Use cached formatter if decimals are undefined
        if (decimals === undefined) {
            return numberFormatter.format(number);
        }

        // Cache and reuse formatters for specific decimal places
        let formatter = formatCache.get(decimals);
        if (!formatter) {
            formatter = new Intl.NumberFormat('en-US', {
                maximumFractionDigits: decimals,
                minimumFractionDigits: decimals,
            });
            formatCache.set(decimals, formatter);
        }

        return formatter.format(number);
    };
</script>

Script Preparation code:

const formatter = new Intl.NumberFormat(undefined, {
    style: 'currency',
    currency: 'RUB',
});

Tests:

Number.toLocaleString
toLocaleString(1000000, 1); toLocaleString(1000000, 2); toLocaleString(1000000, 10); toLocaleString(1000000, 8); toLocaleString(1000000, 12);
Intl.NumberFormat
formatNumber(1000000, 1); formatNumber(1000000, 2); formatNumber(1000000, 10); formatNumber(1000000, 8); formatNumber(1000000, 12);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Number.toLocaleString
Intl.NumberFormat

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Linux; Android 10; K) AppleWebKit/537.36 (KHTML, like Gecko) SamsungBrowser/28.0 Chrome/130.0.0.0 Mobile Safari/537.36

Browser/OS: Chrome Mobile 130 on Android

View result in a separate tab

Intl.NumberFormat

306K/s

Number.toLocaleString

6K/s

View exact numbers

Test name	Executions per second
✓ Intl.NumberFormat	305,706 Ops/sec
Number.toLocaleString	6,190 Ops/sec

cached Number.toLocaleString vs Intl.NumberFormat (version: 1)

Comparing performance of: `Number.toLocaleString vs Intl.NumberFormat`

Created: one year ago by: Registered User

Go to the latest result

Number.toLocaleString

Intl.NumberFormat

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

cached Number.toLocaleString vs Intl.NumberFormat (version: 1)

Comparing performance of: Number.toLocaleString vs Intl.NumberFormat

Created: one year ago by: Registered User

Go to the latest result

Number.toLocaleString

Intl.NumberFormat

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Related benchmarks

Comparing performance of: `Number.toLocaleString vs Intl.NumberFormat`