<style type="text/css">
#shadow, #text { font: 12px/16px Arial; 200px; overflow: hidden; height: 16px; }
#shadow { position: absolute; border- 0px; padding: 0px; visibility: hidden; }
#text { resize: none; }
</style>
<script type="text/javascript">
/*
by VILIC VANE
Web www.vilic.info
Email i@vilic.info
*/
window.onload = function () {
var text = document.getElementById("text"); //用户看到的文本框
var shadow = document.getElementById("shadow"); //隐藏的文本框
text.oninput = //非IE的
text.onpropertychange = //IE的
onchange;
function onchange() {
shadow.value = text.value;
setHeight();
setTimeout(setHeight, 0); //针对IE 6/7/8的延迟, 否则有时会有一个字符的出入
function setHeight() { text.style.height = shadow.scrollHeight + "px"; }
}
};
</script>
<body>
<textarea id="text"></textarea>
<textarea id="shadow"></textarea>
</body>