Javascript regex for amount
/^d+.{0,1}+d{0,2)+$/

/^d+(.d{1,2})?$/

> var re = /^d+(.d{1,2})?$/
  undefined
> re.test('123')
  true
> re.test('123.00')
  true
> re.test('123.')
  false
> re.test('12.34.5')
  false
> re.test('123.000')
  false

/^d+(.d{1,2})?$/

// Check if string is currency
var isCurrency_re    = /^s*(+|-)?((d+(.dd)?)|(.dd))s*$/;
function isCurrency (s) {
   return String(s).search (isCurrency_re) != -1
}