JS控制文本框只能输入N个字符

[转]http://www.phpv.net/article.php/1458

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)
}

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>