How to Add a Thousandths Place Comma (Every Three Digits) in JavaScript
Nick Scialli • December 29, 2020 • 🚀 1 minute read
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Let’s do some basic number formatting for large numbers in JavaScript. If you’re here, you probably to be able to make the following conversions:
- 1000 -> 1,000
- 1000000 -> 1,000,000
- 100 -> 100
You’re in luck: there are a couple fairly simple ways to do this in JavaScript
toLocaleString
One simple option is the built-in toLocaleString string method. It goes something like this:
(1000).toLocaleString('en-US');
// 1,000
(1000000).toLocaleString('en-US');
// 1,000,000
(100).toLocaleString('en-US');
// 1000Regular Expressions
Another option is to use a Regular Expression. If our input is a number, we’ll want to make sure to covert it to a string before applying the regex.
function addCommas(num) {
return num.toString().replace(/(\d)(?=(\d\d\d)+(?!\d))/g, '$1,');
}
addCommas(1000);
// 1,000
addCommas(1000000);
// 1,000,000
addCommas(100);
// 1000And that’s it! A couple fairly straightforward ways to add commas to your large numbers.
Nick Scialli is a software engineer at the U.S. Digital Service.