实时监控输入框,两个输入框数据不为零的时候按钮变色

//判断按钮变色
var invoiceName = 0 ;
var invoiceNumber = 0;
console.log(invoiceName);
//实时监控输入框内容
$(document).on("input propertychange",".invoiceName", function(){
   invoiceName = $(".invoiceName").val().length;
   if(invoiceNumber !=0 && invoiceName !=0){
      $(".invoiceBtn").css({
         "background":"#1da1f2"
      })
   }else {
      $(".invoiceBtn").css({
         "background":"#dcdcdc"
      })
   }
   console.log(invoiceName);


})
$(document).on("input propertychange",".invoiceNumber", function(){
   invoiceNumber = $(".invoiceNumber").val().length;
   if(invoiceName !=0 && invoiceNumber !=0){
      $(".invoiceBtn").css({
         "background":"#1da1f2"
      })
   }else {
      $(".invoiceBtn").css({
         "background":"#dcdcdc"
      })
   }

   console.log(invoiceNumber);
})
//判断按钮变色结束