IBAN input mask that does not work

iban-input-mask-not-working.js

    function applyIBANMaks(input) {
      var mask = '____ ____ ____ ____ ____ ____ ____'.split('');
      var cursorPositionDelta = 0;

      function strip(value) {
        return value.split('').filter(function (chr) {
          return /[a-zA-Z\d]/.test(chr);
        });
      }

      function apply(data, currentCursorPosition) {
        var length = data.length;
        var index = 0;
        return mask.map(function(chr) {
          index++;
          if (index <= length && chr != '_') {
            if (cursorPositionDelta < currentCursorPosition) {
              cursorPositionDelta++;
            }
            return chr;
          }
          return data.shift();
        }).join('');
      }

      function init() {
        input.value = apply(strip(input.value));
      }

      input.addEventListener('click', init);
      input.addEventListener('keyup', function () {
        cursorPositionDelta = 0;
        var start = input.selectionStart;
        var end = input.selectionEnd;
        input.value = apply(strip(input.value), start);
        input.selectionStart = start + cursorPositionDelta;
        input.selectionEnd = end + cursorPositionDelta;
      });
      init(input);
    }

    var selector = '[name="{{ full_name }}[value]"]';
    var input = document.querySelector(selector);
    if (input) {
      applyIBANMaks(input);
    }