jquery判断输入文字个数的统计代码

<span style="font-family:Microsoft YaHei;font-size:12px;">     <script type="text/javascript">
$(function() {
function albumName() {
var text = $("#album_name").val();
var counter = text.length;
$("#numtj var").text(counter);
$(document).keyup(function() {
var text = $("#album_name").val();
var counter = text.length;
$("#name_word").text(counter);
});
}
});
</script></span>

<span style="font-family:Microsoft YaHei;font-size:12px;"><input type="text" maxlength="30" class="int_txt" name="album_name" id="album_name">
<span class="count_txt"><span id="name_word">0</span>/30</span></span>