<input type=text onpaste="return false" onkeypress="a()">数字<script language=javascript>
function a()
{
var k = window.event.keyCode;
if (k < 48 || k > 57){
alert("你输入的不是数字!")
window.event.keyCode = 0 ;}
}
</script>
function a()
{
var k = window.event.keyCode;
if (k < 48 || k > 57){
alert("你输入的不是数字!")
window.event.keyCode = 0 ;}
}
</script>
<form onsubmit="return c(this)">
<input name=num><input type=submit>
</form>
<script>
function c(f){
if(isNaN(f.num.value)|!f.num.value.replace(/\s/g,'')){alert('必须是数字');return false}
return true
}
</script>
onkeypress="var k=event.keyCode; return k>=48&&k<=57"
onpaste="return !clipboardData.getData('text').match(/\D/)"
ondragenter="return false" style="ime-mode:Disabled"
>