DynamicTextarea Example

HTML

<script src="http://github.com/amadeus/DynamicTextarea-Mootools-Class/raw/master/Source/DynamicTextarea.js"></script>
 <textarea id="mytextarea"></textarea><br>
<textarea id="default" style="resize:none"></textarea><br>
<textarea id="default" style="resize:vertical"></textarea>

JavaScript

$("#mytextarea").resizable({
    resize: function() {
        $(this).css({ resize: "both" });
    }
});