A Keyboard Shortcut to Clean Up Phone Numbers, IBANs, etc. Before Pasting

Do you know those situations where you copy something to the clipboard—such as a phone number, a credit card number, or an IBAN—to paste it into a web form, but the form is annoyingly strict and won’t allow spaces, dashes, or parentheses?

To solve this, I came up with a little Hammerspoon module that binds to ⌃⌘V and strips everything except ASCII letters, digits, and plus signs.

Examples:

+49 30 23125-123 → +493023125123
(030) 23125-123 → 03023125123
GB33 BUKB 2020 1555 5555 55 → GB33BUKB20201555555555

Bonus features:

It uses hs.eventtap.keyStrokes(), so it doesn’t perform an actual paste but instead simulates typing the string. This helps with form fields that, for whatever reason, prevent you from pasting into them.
If you accidentally apply it to a canonical UUID or a string containing an @ sign—typically an email address—it preserves the punctuation and only trims surrounding whitespace.

local module = {}

-- Compact identifiers commonly consist only of ASCII letters, digits, and +.
local function sanitizeIdentifier(text)
  return text:gsub("[^A-Za-z0-9+]", "")
end

local function trim(text)
  return text:match("^%s*(.-)%s*$")
end

local function shouldPreserveFormatting(text)
  -- Punctuation is meaningful in email addresses and canonical UUIDs.
  if text:find("@", 1, true) then
    return true
  end

  return text:match("^%x%x%x%x%x%x%x%x%-%x%x%x%x%-%x%x%x%x%-%x%x%x%x%-%x%x%x%x%x%x%x%x%x%x%x%x$") ~= nil
end

local function pasteIdentifier()
  local text = hs.pasteboard.getContents()
  if not text then
    hs.alert.show("Clipboard does not contain text")
    return
  end

  local trimmedText = trim(text)
  local value = shouldPreserveFormatting(trimmedText) and trimmedText or sanitizeIdentifier(text)

  module.pasteTimer = hs.timer.doAfter(0.05, function()
    module.pasteTimer = nil

    -- Let the shortcut's physical Ctrl and Cmd keys come up first. Typing the
    -- cleaned value directly avoids swapping and synchronizing the clipboard.
    hs.eventtap.keyStrokes(value)
  end)
end

function module.start()
  module.hotkeys = {
    hs.hotkey.bind({ "ctrl", "cmd" }, "v", pasteIdentifier),
  }
end

return module

Save it as identifier_paste.lua and include in your init.lua like so:

require("modules.identifier_paste").start()