Javascript Currency Validation

The following will check a string to make sure it is a valid currency. It can only include numbers and a . (decimal point which is optional).

function validateCurrency(amount) {
  var regex = /^[1-9]\d*(?:\.\d{0,2})?$/;
  return regex.test(amount);
}

The amount must start with a number 1 through 9, you can change this to 0-9 but potentially allows someone to put 0.00 so you would have to apply further validation. Then optionally the user can enter a decimal to 2 decimal places.

This validates for:

• 20.00
• 13.12
• 12.5
• 1.00
• 1.50

But fails on:

• 20.000
• 0.50
• 0.2
• 1,500
• 1,200.50