使用Jquery each()循环输入字段进行验证

我正在制作一个表单，只有在输入值为数字时才希望代码执行。我试图避免使用某种验证插件，并且想知道是否有方法循环输入字段并检查值。

我一直在尝试以下，但我认为我的逻辑是错误的：

(#monthlyincome是表单id)

$("#submit").click(function() {

  $("#monthlyincome input").each(function() {

       if (!isNaN(this.value)) {
       // process stuff here

       }

   });

});

有任何想法吗？

这是整个更新的代码：

$("#submit").click(function() {

    $("#monthlyincome input[type=text]").each(function() {
        if (!isNaN(this.value)) {
            // processing data      
            var age         = parseInt($("#age").val());
            var startingage = parseInt($("#startingage").val());

            if (startingage - age > 0) { 

                $("#field1").val(startingage - age);
                $("#field3").val($("#field1").val());

                var inflationyrs    = parseInt($("#field3").val());
                var inflationprc    = $("#field4").val() / 100;
                var inflationfactor = Math.pow(1 + inflationprc,inflationyrs);
                $("#field5").val(inflationfactor.toFixed(2)); 

                var estyearlyinc    = $("#field6").val();
                var inflatedyearlyinc = inflationfactor * estyearlyinc;
                $("#field7").val(FormatNumberBy3(inflatedyearlyinc.toFixed(0),","."));

                var estincyears = $("#field2").val();
                var esttotalinc = estincyears * inflatedyearlyinc;
                $("#field8").val(FormatNumberBy3(esttotalinc.toFixed(0),"."));

                var investmentrate   = $("#field9").val() / 100;
                var investmentfactor = Math.pow(1 + investmentrate,inflationyrs);
                $("#field10").val(investmentfactor.toFixed(2));

                var currentsavings = $("#field11").val();
                var futuresavings  = currentsavings * investmentfactor;
                $("#field12").val(FormatNumberBy3(futuresavings.toFixed(0),"."));

                //final calculations
                var futurevalue = (1 * (Math.pow(1 + investmentrate,inflationyrs) - 1) / investmentrate);
                var finalvalue = (1 / futurevalue * (esttotalinc - futuresavings));

                $("#field13").val(FormatNumberBy3(finalvalue.toFixed(0),"."));

            }
            // end processing
        }
    });

});

FormatNumberBy3是用于…格式化数字的函数。