簡單實現代碼如下：
$("#rewardForm").validate({
rules: {
"reward": {
required: true,
digits:true,
balance:true,
checkBalance:true
}
}, messages:{
"reward":{
digits:" * 請填寫正確的轉賬金額（應為數字）",
required:" * 請輸入轉賬金額 "
}
}
});

jQuery.validator.addMethod("balance", function(value,element) {
var sumreward=$("#sumreward").val();
return this.optional(element) || value<= sumreward;
}, $.validator.format(" * 余額不足 "));

jQuery.validator.addMethod("checkBalance", function(value,element) {
var balance=0;
return this.optional(element) || value>balance;
}, $.validator.format(" * 轉賬金額必須大于0 "));