急！！判断数字

Question

http://expert.csdn.net/Expert/TopicView2.asp?id=1400466&datebasetype=now

Answer 1

http://expert.csdn.net/Expert/TopicView2.asp?id=1415594&datebasetype=now

Answer 2

包括整数、小数、日期等多种输入验证：
http://jkisjk.vip.sina.com/code/html/inputcheck.htm

Answer 3

<script>
a="2";
if(isNaN(a)){
  alert("not a number!");
}else{
  alert("a number!");
}
</script>

Answer 4

<input name=a onkeypress="checkKeyPressNumAndPercent()" onblur="checkNum(this)">
<SCRIPT LANGUAGE="JavaScript">
<!--
function checkNum(thisObj)
{
   if(isNaN(thisObj.value)){
      alert("只允许输入数字！");
      thisObj.value=0;
   }
}function checkKeyPressNumAndPercent()
{
  try{
      if ((window.event.keyCode<48 && window.event.keyCode!=46) || window.event.keyCode>58) 
         {
          window.event.keyCode=0;
          return false;
         }
     }catch(e){alert(e.description);}
}
//-->
</SCRIPT>