Formatting numbers is key to many applications. This may seem like a small task to an experienced developer, but the thought of having to write these for every application I start is disheartening. Well, anyways, enough with my rant. Let's look for a library to knock this out so we can move on. We need a solution that handles percentages, currency, and many languages. Hmm? What if there was an API in the browser?

Using Intl.NumberFormat

The Intl.NumberFormat API can handle percentages, decimals, currencies and locale. Let's check it out.

Adding commas where needed

Intl.NumberFormat().format(40000); // 40,000

Need support for Spanish?

Intl.NumberFormat('es').format(40000); // 40.000

Currency is a tricky one.

Intl.NumberFormat("en-US", {
  style: "currency",
  currency: "USD"
}).format(40000); // $40,000.00

Currency Again, Spanish?

Intl.NumberFormat("es", {
  style: "currency",
  currency: "USD"
}).format(40000); // 40.000,00 US$

Other Examples

I'll keep this short and sweet. I encourage you, next time you reach for a library to solve a problem, look to the platform first!

References

MDN: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/NumberFormat
Browser Support: https://caniuse.com/#search=NumberFormat