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javascript - 当获得两个不同函数中的两个变量的总数时，结果为 NaN

问题描述

为什么在访问 2 个不同函数的变量时会得到 NaN 结果？

我的代码

    var n_standard = 0;
    var n_quad = 0;
    var totalQuad;
    var totalStandard;
    var total = totalStandard + totalQuad;
    function standardRoom(){
      n_standard = n_standard + Number($("#selectBoxStandard").val());
      var xSumStandard = Number($("#n_adultStandard").val()) + Number($("#n_childrenStandard").val());
      totalStandard = {{$availableRooms[0]['nightRate'] * $n_nights }} * n_standard;

      if ($('select#selectBoxStandard option').length > 1 && Number($("#selectBoxStandard").val()) !== 0) {
        $('#selectBoxStandard').find("option:nth-last-child(-n+" + $('#selectBoxStandard').val() + ")").remove();
            $("#roomDetailStandard ul").html('<li><strong>Standard Room - Regular Online Rate</strong> <strong><a href="javascript:removeStandard()" class="pull-right" style="color:red"><u>remove</u></a></strong></li>'+
            '<li class="pull-right"><h4 style="color:darkorange">PHP ' + totalStandard + '</h4></li>'+
            '<li>Number of night(s): {{$n_nights}} </li>'+
            '<li>Number of person(s): ' + xSumStandard + '</li>'+
            '<li class="hr">Number of room(s): '+ n_standard +'</li><hr />'
          );
          $("#totals ul").html('<li>Total:'+ total +'</li>');
          return totalStandard;


      }else {
        alert("Select No. of rooms");
      }
    }

       function quadRoom(){
        n_quad = n_quad + Number($("#selectBoxQuad").val());
       var xSumQuad = Number($("#n_adultQuad").val()) + Number($("#n_childrenQuad").val());
       totalQuad = {{$availableRooms[1]['nightRate'] * $n_nights}} * n_quad;

      if ($('select#selectBoxQuad option').length > 1 && Number($("#selectBoxQuad").val()) !== 0) {
         $('#selectBoxQuad').find("option:nth-last-child(-n+" + $('#selectBoxQuad').val() + ")").remove();
             $("#roomDetailQuad ul").html('<li><strong>Quad Room - Regular Online Rate</strong> <strong><a href="javascript:removeQuad()" class="pull-right" style="color:red"><u>remove</u></a></strong></li>'+
                '<li class="pull-right"><h4 style="color:darkorange">PHP ' + totalQuad + '</h4></li>'+
                '<li>Number of night(s): {{$n_nights}} </li>').append('<li>Number of person(s): ' + xSumQuad + '</li>'+
                '<li class="hr">Number of room(s): '+ n_quad +'</li><hr />'
              );
              $("#totals ul").html('<li>Total:'+ total +'</li>');
              return totalQuad;

      }else {
          alert("Select No. of rooms");
      }
    }


<div  class="button-style-1" style="padding-bottom:80px" style="padding-bottom:40px"><a href="javascript:standardRoom()" ><i class="fa fa-calendar"></i><span class="mobile-visibility">BOOK</span></a></div>
<div class="button-style-1" style="padding-bottom:80px" style="padding-bottom:40px"><a href="javascript:quadRoom()" ><i class="fa fa-calendar"></i><span class="mobile-visibility">BOOK</span></a></div>

我试图返回totalStandard和totalQuad然后将它们加在一起​​total，然后将它们输出回函数中。我在这里遗漏了一些东西，我是 javascript 新手，所以我需要一些帮助

标签： javascriptjqueryajax

解决方案

  n_standard = n_standard + Number($("#selectBoxStandard").val());
  var xSumStandard = Number($("#n_adultStandard").val()) + 
  Number($("#n_childrenStandard").val());
  totalStandard = {{$availableRooms[0]['nightRate'] * $n_nights }} * n_standard;

这段代码和你计算 totalQuad 的地方应该被数字检查函数包围，以确保变量是数字。例如，为了确保每次只取数字，您可以检查if($.isNumeric($availableRooms[0]['nightRate'])){.......}. 如果任何变量不是数字，则结果将为 NaN。所以请在数学运算之前检查每个数字变量。编辑：var totalQuad; var totalStandard; var total = totalStandard + totalQuad; totalStandard=9; console.log("result="+total); 这将导致 NaN，因为我没有在这里定义 totalQuad 变量。如果首先将两个变量都初始化为 0，那将起作用。 第二次编辑： 

    var totalQuad;
    var totalStandard;
    var total = totalStandard + totalQuad;
    function standardRoom(){
      totalStandard=9;
    }

       function quadRoom(){
        totalQuad=5;
    }

    function Total()
    {
      console.log(totalStandard);
      console.log(totalQuad);
      console.log(total); // THIS will RESULT IN NaN, as WHEN Total variable initialized, totalStandard and totalQuad are not initialized then. Latter initialization doesn't reinitialize total value
      console.log("Total="+(totalStandard*totalQuad));
    }
<div  class="button-style-1" style="padding-bottom:80px" style="padding-bottom:40px"><a href="javascript:standardRoom()" ><i class="fa fa-calendar"></i><span class="mobile-visibility">BOOK</span></a></div>
<div class="button-style-1" style="padding-bottom:80px" style="padding-bottom:40px"><a href="javascript:quadRoom()" ><i class="fa fa-calendar"></i><span class="mobile-visibility">BOOK</span></a></div>
<div class="button-style-1" style="padding-bottom:80px" style="padding-bottom:40px"><a href="javascript:Total()" ><i class="fa fa-calendar"></i><span class="mobile-visibility">Total</span></a></div>

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