There was another thread about this, which I’ve tried. But there is one problem: the textarea doesn’t shrink if you delete the content. I can’t find any way to shrink it to the correct size – the clientHeight value comes back as the full size of the textarea, not its contents.
The code from that page is below:
function FitToContent(id, maxHeight){ var text = id && id.style ? id : document.getElementById(id); if ( !text ) return; var adjustedHeight = text.clientHeight; if ( !maxHeight || maxHeight > adjustedHeight ) { adjustedHeight = Math.max(text.scrollHeight, adjustedHeight); if ( maxHeight ) adjustedHeight = Math.min(maxHeight, adjustedHeight); if ( adjustedHeight > text.clientHeight ) text.style.height = adjustedHeight + "px"; }}window.onload = function() { document.getElementById("ta").onkeyup = function() { FitToContent( this, 500 ) };}Advertisement
Answer
This works for me (Firefox 3.6/4.0 and Chrome 10/11):
var observe;if (window.attachEvent) { observe = function (element, event, handler) { element.attachEvent('on'+event, handler); };}else { observe = function (element, event, handler) { element.addEventListener(event, handler, false); };}function init () { var text = document.getElementById('text'); function resize () { text.style.height = 'auto'; text.style.height = text.scrollHeight+'px'; } /* 0-timeout to get the already changed text */ function delayedResize () { window.setTimeout(resize, 0); } observe(text, 'change', resize); observe(text, 'cut', delayedResize); observe(text, 'paste', delayedResize); observe(text, 'drop', delayedResize); observe(text, 'keydown', delayedResize); text.focus(); text.select(); resize();}textarea { border: 0 none white; overflow: hidden; padding: 0; outline: none; background-color: #D0D0D0;}<body onload="init();"><textarea rows="1" style="height:1em;" id="text"></textarea></body>If you want try it on jsfiddle
It starts with a single line and grows only the exact amount necessary. It is ok for a single textarea, but I wanted to write something where I would have many many many such textareas (about as much as one would normally have lines in a large text document). In that case it is really slow. (In Firefox it’s insanely slow.) So I really would like an approach that uses pure CSS. This would be possible with contenteditable, but I want it to be plaintext-only.