function grow() { var textarea = document.getElementById('growingTextarea'); var newHeight = textarea.scrollHeight; var currentHeight = textarea.clientHeight;…}
if (newHeight > currentHeight) { textarea.style.height = newHeight + 5 * TEXTAREA_LINE_HEIGHT + 'px';}
<script>// Value of the line-height CSS property for the textarea.var TEXTAREA_LINE_HEIGHT = 13;function grow() { var textarea = document.getElementById('growingTextarea'); var newHeight = textarea.scrollHeight; var currentHeight = textarea.clientHeight; if (newHeight > currentHeight) { textarea.style.height = newHeight + 5 * TEXTAREA_LINE_HEIGHT + 'px'; }}</script><textarea id="growingTextarea" onkeyup="grow();"></textarea>
