// Listener on column 2 inputs
$('.answer-item.column-2 input:text', thisQuestion).on('keyup change', function(e) {
  var thisValue = $.trim($(this).val());
 
  // Strip out non-numerics characters
  newValue = thisValue.replace(/\D/g,'').replace(/,/g,'').replace(/\./g,'');
  $(this).val(newValue).trigger('change');
});

<script type="text/javascript" charset="utf-8">
$(document).on('ready pjax:scriptcomplete',function(){
    var thisQuestion = $('#question{QID}');
 
    // Column-specific classes
    $('tr.subquestion-list', thisQuestion).each(function(i) {
      $('th, td', this).each(function(i) {
        $(this).addClass('column-'+i);
      });
    });
 
    // Insert selects into column 1
    if($('.answer-item.column-1 .inserted-select', thisQuestion).length == 0) {
      $('.answer-item.column-1', thisQuestion).addClass('with-select').append('<select class="inserted-select form-control list-question-select">\
        <option value="">Please choose...</option>\
        <option value="1">Yes</option>\
        <option value="2">No</option>\
        <option value="3">Do not know</option>\
      </select>');
    } 
 
    // Listeners on select elements
    $('.inserted-select', thisQuestion).on('change', function(i) {
      if($(this).val() != '') {
        $(this).closest('.answer-item').find('input:text').val($.trim($('option:selected', this).text())).trigger('change');
      }
      else {
        $(this).closest('.answer-item').find('input:text').val('').trigger('change');
      }
    });

    // Listener on column 2 inputs
    $('.answer-item.column-2 input:text', thisQuestion).on('keyup change', function(e) {
      var thisValue = $.trim($(this).val());
 
      // Numerics only
      if($.isNumeric(thisValue) === false) {
 
        // Strip out non-numerics characters
        newValue = thisValue.replace(/\D/g,'');
        $(this).val(newValue).trigger('change');
      }
});
 

    // Returning to page
    $('.with-select input:text', thisQuestion).each(function(i) {
      var thisCell = $(this).closest('.answer-item');
      var inputText = $.trim($(this).val());
      var selectval = $('select.inserted-select option', thisCell).filter(function () { return $(this).html() == inputText; }).val();
      $('select.inserted-select', thisCell).val(selectval);
    });
 
 
    // Clean-up styles
    $('select.inserted-select', thisQuestion).css({
      'max-width': '100%'
    });
    $('.with-select input:text', thisQuestion).css({
      'position': 'absolute',
      'left': '-9999em'
    });
  });
 
</script>

I did that but it still doesn't work. I don't know where the Problem lies.