JS函数isNaN() 判断数字
<html>
<body>
<input name="" id="t" type="text" value="0" onchange="isNumber()"/>
</body>
</html>
<script>
function isNumber(){
var t = document.getElementById('t').value;
if(!isNaN(t)){
alert("是数字");
}else{
alert("不是数字");
}
}
</script>