"Oops! That does not apperar to be a valid number. Please try again"这是由于什么原因引起的错误？

Question

<INPUT type="Textbox" onKeyDown="javascript:okd(event,this)" onChange="javascript:ocv()" name="floatgrpidField" id="floatgrpidField" value="" style=" visibility: hidden; position: absolute; left: -500; top: -500" onBlur="isInteger(this.value);"/>
<script language="javascript">
function okd(e,t){
var keyVal = key(e);
if(keyVal==13){
alert("onkeydown");
}
}
function ocv(){
alert("onChanged");
}
</script>
在input 中输入回车后，就会提示上面信息，然后才弹出alert提示框