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Number.prototype.toLocaleString()

number.toLocaleString(locales, options)

Returns the number as a string in the form usual for the given language – in American English with commas between thousands and a decimal point, in German the other way round. The options handle a currency, percentages and the number of decimal places.

Parameters

locales – optional, for example 'en-US'.
options – optional, for example style: 'currency', currency: 'USD', style: 'percent', minimumFractionDigits, maximumFractionDigits.

Return value

A string.

Examples

console.log((1234567.891).toLocaleString('en-US'));
console.log((1234.5).toLocaleString('en-US', { style: 'currency', currency: 'USD' }));
console.log((0.215).toLocaleString('en-US', { style: 'percent', maximumFractionDigits: 1 }));
console.log((1234.5).toLocaleString('de-DE', { minimumFractionDigits: 2 }));

Output:

1,234,567.891
$1,234.50
21.5%
1.234,50

Things to watch out for

Some languages (French, Czech) use a non-breaking space as the thousands separator, not an ordinary one – keep that in mind when comparing strings or in tests.
Always state the language, otherwise the result depends on the browser settings.
When formatting many numbers, one new Intl.NumberFormat('en-US', options) and its format() is faster.

Browser support

Baseline – widely available: works in all major browsers and has for a long time (since 2015 at the latest). Since version: Chrome 1, Firefox 1, Safari 1; Node.js 0.10.0. As of October 2026 (MDN browser-compat-data).