UK Currency Regular Expression for javascript

Question

Hi

I'm after a regular expression that matches a UK Currency (ie. £13.00, £9,999.99 and £12,333,333.02), but does not allow negative (-£2.17) or zero values (£0.00 or 0).

I've tried to create one myself, but I've got in a right muddle!

Any help greatfully received.

Thanks!

Answer 1

This'll do it (well mostly...)

/^£?[1-9]{1,3}(,\d{3})*(\.\d{2})?$/

Leverages the ^ and $ to make sure no negative or other character is in the string, and assumes that commas will be used. The pound symbol, and pence are optional.

edit: realised you said non-zero so replaced the first \d with [1-9]

Update: it's been pointed out the above won't match £0.01. The below improvement will but now there's a level of complexity where it may quite possibly be better to test /[1-9]/ first and then the above - haven't benchmarked it.

/^£?(([1-9]{1,3}(,\d{3})*(\.\d{2})?)|(0\.[1-9]\d)|(0\.0[1-9]))$/

Brief explanation:

• Match beginning of string followed by optional "£"
• Then match either:
  • a >£1 amount with potential for comma separated groupings and optional pence
  • OR a <£1 >=£0.10 amount
  • OR a <=£0.09 amount
• Then match end of line

The more fractions of pence (zero in the above) you require adding to the regex the less efficient it becomes.

Answer 2

You could just make two passes:

/^£\d{1,3}(,\d{3})*(\.\d{2})?$/

to validate the format, and

/[1-9]/

to ensure that at least one digit is non-zero.

This is less efficient than doing it in one pass, of course (thanks, annakata, for the benchmark information), but for a first implementation, just "saying what you want" can significantly reduce developing time.