HTML的TextArea标记跟随文本内容自动设置高度

<script type="text/javascript">
function get_text_rows(text) {
return text.split("\n").length;
}
$(document).ready(function () {
document.getElementById('ctl00_jiSubCon_txtJobDescribe').rows = get_text_rows($('#ctl00_jiSubCon_txtJobDescribe').val());
document.getElementById('ctl00_jiSubCon_txtJobNeed').rows = get_text_rows($('#ctl00_jiSubCon_txtJobNeed').val());
document.getElementById('ctl00_jiSubCon_txtContactMode').rows = get_text_rows($('#ctl00_jiSubCon_txtContactMode').val());
});
</script>
<script>
var textarea = document.getElementById('ctl00_jiSubCon_txtJobDescribe');
textarea.style.height = textarea.scrollHeight + 'px';
var textarea2 = document.getElementById('ctl00_jiSubCon_txtJobNeed');
textarea2.style.height = textarea2.scrollHeight + 'px';
var textarea3 = document.getElementById('ctl00_jiSubCon_txtContactMode');
textarea3.style.height = textarea3.scrollHeight + 'px';
</script>
http://my.oschina.net/ldaga/blog/156399