How to Internationalize Numbers with JavaScript

By  on  

Presenting numbers in a readable format takes many forms, from visual charts to simply adding punctuation. Those punctuation, however, are different based on internationalization. Some countries use , for decimal, while others use .. Worried about having to code for all this madness? Don't -- JavaScript provides a method do the hard work for you!

The Number primitive has a toLocaleString method to do the basic formatting for you:

const price = 16601.91;

// Basic decimal format, no providing locale
// Uses locale provided by browser since none defined
price.toLocaleString(); // "16,601.91"

// Provide a specific locale
price.toLocaleString('de-DE'); // "16.601,91"

// Formatting currency is possible
price.toLocaleString('de-DE', { 
  style: 'currency', 
  currency: 'EUR' 
}); // "16.601,91 €"

// You can also use Intl.NumberFormat for formatting
new Intl.NumberFormat('en-US', {
  style: 'currency',
  currency: 'GBP'
}).format(price); // £16,601.91

It's a major relief that JavaScript provides us these type of helpers so that we don't need to rely on bloated third-party libraries. No excuses -- the tool is there!

Recent Features

  • By
    CSS @supports

    Feature detection via JavaScript is a client side best practice and for all the right reasons, but unfortunately that same functionality hasn't been available within CSS.  What we end up doing is repeating the same properties multiple times with each browser prefix.  Yuck.  Another thing we...

  • By
    CSS Animations Between Media Queries

    CSS animations are right up there with sliced bread. CSS animations are efficient because they can be hardware accelerated, they require no JavaScript overhead, and they are composed of very little CSS code. Quite often we add CSS transforms to elements via CSS during...

Incredible Demos

Discussion

  1. Simple usage without specifying a locale returns a formatted string in the default locale and with default options.

    const number = 3500;
    
    console.log(new Intl.NumberFormat().format(number));
    // '3,500' if in US English locale
    

    See more options with dashingarts.

  2. Is there any difference in the formatting between

    toLocaleString

    and format using

    new Intl.NumberFormat(...)

Wrap your code in <pre class="{language}"></pre> tags, link to a GitHub gist, JSFiddle fiddle, or CodePen pen to embed!