JavaScript Array toLocaleString() Method

The Array.toLocaleString() method is a built-in JavaScript function that converts the elements of an array into a localized string. This method is useful when working with date, number, or custom object data that should be represented in a locale-sensitive manner.

Syntax

arr.toLocaleString(locales, options);

Parameters

Parameter	Description
locales	(Optional) A string or array of strings that represents a BCP 47 language tag, specifies the locale. If omitted, the default locale of the runtime environment is used.
options	(Optional) An object that specifies locale-specific formatting options. These options are passed to the toLocaleString() method of the individual elements.

Return Value

The toLocaleString() method returns a localized string representing the array’s elements, separated by a locale-specific separator.

Example 1: Using Default Locale

let arr = ['HTML', 'CSS', 'JavaScript'];
let str = arr.toLocaleString();
console.log(str); 
// Output: "HTML,CSS,JavaScript"

Example 2: Formatting Numbers

let arr = [123456.789, 987654.321];

let str = arr.toLocaleString('en-US');
console.log(str); 
// Output: "123,456.789,987,654.321"

Example 3: Formatting Dates

let dates = [new Date('2024-01-01'), new Date('2024-12-31')];
let localizedString = dates.toLocaleString('en-GB');
console.log(localizedString); // Output: "01/01/2024,31/12/2024"

Example 4: Customizing Number Formatting

let prices = [1234.5, 5678.9];
let localizedString = prices.toLocaleString('de-DE', { style: 'currency', currency: 'EUR' });
console.log(localizedString); // Output: "1.234,50 €,5.678,90 €"

Example 5: Combining Data Types

let data = [12345.67, new Date('2024-01-01'), 'hello'];

let localizedString = data.toLocaleString('en-US', { style: 'currency', currency: 'USD' });
console.log(localizedString);
// Output: "$12,345.67,1/1/2024,hello"

Supported Browsers

Browser	Support
Chrome	1+
Firefox	1+
Safari	1+
Edge	12+
Opera	4+
Internet Explorer	5.5+