[转]http://www.phpv.net/article.php/1458
下面的文本框,只能输入十个字符
<script type="text/javascript">
function ismaxlength(obj){
var mlength=obj.getAttribute? parseInt(obj.getAttribute("maxlength")) : ""
if (obj.getAttribute && obj.value.length>mlength)
obj.value=obj.value.substring(0,mlength)
}
</script>
<textarea maxlength="10" onkeyup="return ismaxlength(this)"></textarea>