In der Höhe anpassbare Textarea und duplizierbare Formularfelder

Hat grosse Probleme in den alten IE.

HTML

<script src="https://raw.github.com/padolsey/jQuery.fn.autoResize/master/jquery.autoresize.js"></script>
<div id="ta1" class="clearfix" data-id="1">
      <label for="textarea-1">Textarea</label>
      <textarea name="textarea-1" id="textarea-1" cols="30" rows="1"></textarea>
</div>
<div id="ta2" class="clearfix" data-id="2">
      <label for="textarea-2">Textarea</label>
      <textarea name="textarea-2" id="textarea-2" cols="30" rows="1"></textarea>
</div>
<button class="btnAdd">neue Zeile hinzufügen</button>

CSS

body {padding: 40px;}
div { margin-bottom: 10px;}
    label, textarea {display: block;}
    textarea {
        width: 60%;
        background-color: #ddd; 
        border: none;border-bottom: 1px solid #a20000; border-right: 1px solid #a20000;
        font-size: 12px;
        height: 14px;
        min-height: 14px;
        line-height: 1.25;
        }
    button {
        border: 1px solid #999;
        background-color: #a20000;
        color: #fff;
        padding: 5px;
        margin-top: 10px;
    }

JavaScript

$(document).ready(function() {
        
        // https://github.com/padolsey/jQuery.fn.autoResize
        $('textarea').autoResize({
            extraSpace:14,
            minHeight: 14
            });
        
        
        // Grundidee: http://charlie.griefer.com/blog/2009/09/17/jquery-dynamically-adding-form-elements/

        $('.btnAdd').on('click', function(e) {

            var num = $(this).prev().attr("data-id");
            var num = new Number(num);
            var newNum  = num+1;
            
            var newElem = $('#ta' + num).clone().attr({
                                id: 'ta' + newNum,
                                'data-id': newNum
                            });
            
            newElem.children("label").attr("for", "textarea" + newNum).end()
                   .children('textarea').attr({
                    id: 'textarea' + newNum,
                    name: 'textarea' + newNum   
                   });
            $('#ta' + num).after(newElem);
                        
            e.preventDefault();
        });       
       
    });