如何在Function中使用Keyup功能？

Question

$(".main_calculations").delegate( '#advance_payment', '#discount', "keyup", function() 

該功能不起作用。 有誰知道這是怎么做到的嗎？

function totalbal() {
  var tot = 0;
  $("#total").each(function() {
    if (!isNaN(this.value) && this.value.length != 0) {
      tot = parseFloat(this.value);
    }
  });

  console.log(tot);

  $(".main_calculations").delegate('#advance_payment', '#discount', "keyup", function() {
    var total = parseInt(document.getElementById("advance_payment").value);
    var val2 = parseInt(document.getElementById("discount").value);
    // to make sure that they are numbers

    if (!total) {
      total = 0;
    }

    if (!val2) {
      val2 = 0;
    }

    var ansD = document.getElementById("total_balance");
    ansD.value = tot - (total - val2);
  });
}

Answer 1

語法問題

 $(".main_calculations").delegate('#advance_payment', '#discount', "keyup", function() {

它應該是.delegate( selector, eventType, handler )

 $(".main_calculations").delegate( '#advance_payment, #discount', "keyup",  function() {

因此，根據所有建議使用

 $(".main_calculations").on("keyup", '#advance_payment, #discount', function() {

Answer 2

嘗試這個：

    function totalbal() {
    var tot = 0;
    $("#total").each(function() {
    if (!isNaN(this.value) && this.value.length != 0) {
    tot = parseFloat(this.value);
    }
    });

    console.log(tot);

    $(".main_calculations").delegate('#advance_payment,#discount', "keyup", 
   function() {
   var total = parseInt(document.getElementById("advance_payment").value);
   var val2 = parseInt(document.getElementById("discount").value);
   // to make sure that they are numbers

   if (!total) {
  total = 0;
   }

   if (!val2) {
    val2 = 0;
   }

    var ansD = document.getElementById("total_balance");
    ansD.value = tot - (total - val2);
    });
    }