Format number with commas

format-commas.js

// Converts "1234567.89" => "1,234,567.89"
function formatNumberWithCommas(number) {
    const parts = number.split('.')
    return ('' + parts[0])                      // Convert to a string
        .split('').reverse().join('')           // Reverse the order of the characters (which are all digits at this point)
        .replace(/(...)/g, '$1,')               // Insert a comma after every three digits
        .split('').reverse().join('')           // Un-reverse the characters
        .replace(/^,/, '')                      // Remove any commas that were added to the beginning (i.e. if the number of digits was a multiple of three)
        .concat(parts[1] ? '.' + parts[1] : '') // Re-add the decimal, if any
}

This is a really cool technique mate!

You can support decimal pretty easily.

function formatNumberWithCommas (number) {
  var num = number.split('.');
  return ('' + num[0])
  .split('').reverse().join('')
  .replace(/(...)/g, '$1,')
  .split('').reverse().join('')
  .replace(/^,/, '')
  .concat('.' + num[1]);
};
console.log(formatNumberWithCommas("1000000.23"));

Awesome, thanks! Works great, I'll add it.

Oh yeah! Nice one mate!! 🤟