commaString = function (input) {
  if (isNaN(input)) { return 0; }

  const parts = input.toString().split('.');
  parts[0] = parts[0].replace(/\B(?=(\d{3})+(?!\d))/g, ',');
  return parts.join('.');
}
Adds commas to a number so it's easier to read

@example
'{{ 123456789 | commaString }}'
this.$options.filters.commaString(123456789);

@param {int} input The number to add commas to
@returns {string}  The number string with commas