JavaScript数字微调

来源：http://hi.baidu.com/adverse/blog/item/3682bfa1480b2c8a471064fa.html

<SCRIPT LANGUAGE="JavaScript" defer>
<!--
function scrollTextarea(obj)
{
     var textareaMin = 1
     var textareaMax = 255
     var o_Top = obj.scrollTop
     if (obj.scrollTop == 2)
     {
         obj.value = (parseInt(obj.value) > textareaMax-1)?textareaMin:(parseInt(obj.value)+1)
     }
     else if (obj.scrollTop == 0)
     {
         obj.value = (parseInt(obj.value) < textareaMin+1)?textareaMax:(parseInt(obj.value)-1)
     }
     obj.scrollTop = 1
}
function IntTextarea(obj)
{
     obj.scrollTop = 1
}
IntTextarea(document.getElementById("num"))
//-->
</SCRIPT>
<textarea onscroll=scrollTextarea(this); readonly onselectstart="return false" class="input" style="ime-mode:disabled;" rows="1" name="num" cols="4" id="num">128</textarea>