Intl.NumberFormat

var number = 3500;

console.log(new Intl.NumberFormat().format(number));
// → '3,500' if in US English locale

var number = 123456.789;

// German uses comma as decimal separator and period for thousands
console.log(new Intl.NumberFormat('de-DE').format(number));
// → 123.456,789

// Arabic in most Arabic speaking countries uses real Arabic digits
console.log(new Intl.NumberFormat('ar-EG').format(number));
// → ١٢٣٤٥٦٫٧٨٩

// India uses thousands/lakh/crore separators
console.log(new Intl.NumberFormat('en-IN').format(number));
// → 1,23,456.789

// the nu extension key requests a numbering system, e.g. Chinese decimal
console.log(new Intl.NumberFormat('zh-Hans-CN-u-nu-hanidec').format(number));
// → 一二三,四五六.七八九

// when requesting a language that may not be supported, such as
// Balinese, include a fallback language, in this case Indonesian
console.log(new Intl.NumberFormat(['ban', 'id']).format(number));
// → 123.456,789

var number = 123456.789;

// request a currency format
console.log(new Intl.NumberFormat('de-DE', { style: 'currency', currency: 'EUR' }).format(number));
// → 123.456,79 €

// the Japanese yen doesn't use a minor unit
console.log(new Intl.NumberFormat('ja-JP', { style: 'currency', currency: 'JPY' }).format(number));
// → ￥123,457

// limit to three significant digits
console.log(new Intl.NumberFormat('en-IN', { maximumSignificantDigits: 3 }).format(number));
// → 1,23,000

console.log(new Intl.NumberFormat('pt-PT',  {
    style: 'unit',
    unit: 'kilometer-per-hour'
}).format(50));
// → 50 km/h

console.log((16).toLocaleString('en-GB', {
    style: 'unit',
    unit: 'liter',
    unitDisplay: 'long'
}));
// → 16 litres