JS实现：0-10数字输入框，自动保留两位小数并校验

页面部分：
<table class="section" border="0" cellspacing="0" cellpadding="0">
    <tr class="trTwo">
        <td>号码：</td>
        <td><input type="text" class="inputTextStyle" id="presentPhoneNum" placeholder="请输入号码"/></td>
        <td><span class="mLeft">金额：</span></td>
        <td><input type="text" class="inputTextStyle" id="presentAmount" placeholder="不超过10元"/></td>
    </tr>
    <tr class="trThree">
    <td><input type="text" style="display: none" id="phoneNumErrorFlag" value="0"/></td>
    <td height="22px"><span class="prcieError" style="display: none" id="presentPhoneNumError">请正确录入号码</span></td>
    <td><input type="text" style="display: none" id="amountErrorFlag" value="0"/></td>
    <td height="22px"><span class="prcieError" style="display: none" id="presentAmountError">请正确录入金额</span></td>
    </tr>
</table>
js部分：
$("#presentAmount").live("keyup",function(){
    $("#presentAmountError").hide();
    var price = $.trim($("#presentAmount").val());
    if(price == "" && price == "") {
        $("#amountErrorFlag").attr("value", "0");
        return true;
    }
    var patt = new RegExp("^[0-9]{1}(\\.([0-9]{0,2}))?$|^10(\.[0]{0,2})?$");
    if(!patt.test(price) || !patt.test(price)) {
        $("#presentAmountError").show();
        $("#amountErrorFlag").attr("value", "0");
        return false;
    }
    $("#amountErrorFlag").attr("value", "1");