Regular Expression for formatting numbers in JavaScript

Question

I need to display a formatted number on a web page using JavaScript. I want to format it so that there are commas in the right places. How would I do this with a regular exp

Answer 1

I think you would necessarily have to do multiple passes to achieve this with regular expressions. Try the following:

1. Run a regex for one digit followed by 3 digits.
2. If that regex matches, replace it with the first digit, then a comma, then the next 3 digits.
3. Repeat until (1) finds no matches.