[wtmt]

> use things like Intl.NumberFormat in the browser, rather than home-grown 'group 3 digits and insert a comma then join again'.

That home grown solution wouldn’t work in many western countries either, where comma is a decimal separator and dot/period is the thousands separator.

[OJFord]

Yep, true. But don't be tempted just to iterate on it to take account of that and whatever you discover next!