customInputFilter (e, filter) ->
  input = $ e.currentTarget
  value = input.val()
  range = input.caretRange()
  newRange =
    start: range.start
    end: range.end
  newValueGetter = (val) ->
    result = ''
    for i in [0..val.length]
      c = val.charAt i
      if filter.test c
        result += c
      else
        newRange.start-- if range.start >= i
        newRange.end-- if range.end >= i
    result
  newValue = newValueGetter value

  input.val newValue
  input.caretRange newRange