textarea高度自适应

http://jsfiddle.net/hmelenok/WM6Gq/

<textarea type="text" id="title" rows="1">content</textarea>

#title {
    word-break: break-all;
    overflow: hidden; //IMPORTANT! 不加这一句会换行错误
}

$("#title").keydown(function () {
　　var element = this;
　　//setTimeout=0一定要写
    window.setTimeout(function () {
        element.style.height = 'auto';
        element.style.height = (element.scrollHeight) + 'px';
    }, 0);
});