<script>
function aa()
{
var a=document.form1.text1.value
if(a==0|(parseInt(a)%2==1|parseInt(a)%2==0)
{
}
else
{
alert("您输入的不是数字")
}
// abc=setTimeout("aa()",1)
}
<form name="form1">
<input type="text" name="text1">
<input type="submit" onclick="aa()">
</form>
或
<form name="form1">
<input type="text" name="text1" onblue="aa()">
<input type="submit">
</form>
或
<body onload="aa()">
function aa()
{
var a=document.form1.text1.value
if(a==0|(parseInt(a)%2==1|parseInt(a)%2==0)
{
}
else
{
alert("您输入的不是数字")
}
// abc=setTimeout("aa()",1)
}
<form name="form1">
<input type="text" name="text1">
<input type="submit" onclick="aa()">
</form>
或
<form name="form1">
<input type="text" name="text1" onblue="aa()">
<input type="submit">
</form>
或
<body onload="aa()">
<script language="JavaScript">
<!--
function Check(iNum) /*----*/
{
var reg = /^\d+$/;
if(!iNum)
{
alert("你还没输入呢!");
}
else
{
var a = reg.test(iNum);
if(a)
alert("是数字!");
else
alert("不是数字!");
}
}
//-->
</script>
用isNaN大致可以吧!