提交按钮判断式显示按钮与否

$('#name').change(function(event) {
/* Act on the event */
var txtVal=$(this).val();
if (txtVal=="") {
    $('#btn').attr('disabled',"true");   
}else{
    $('#btn').attr('disabled',"false");  
}

});

或者：

<input type="text" id="inpnumber" name="inpnumber"  onkeyup="this.value=this.value.replace(/[^0-9]/g,'')" />

<input type="button" language="javascript" onclick="return btnapply()" id="btn" name="btn"
value="提 交" />

<script type="text/javascript" language="javascript">

function btnappley()

{

var inpnumber=document.getElementById("#inpnumber").val();

if(inpnumber=="")

{

alert("为空则按钮还能显示")

}

else{

$('#inpnumber').attr('disabled', "true");

}

}

</script>