Question

我正在使用以下代码添加文本框值，如果没有给出任何文本框值，它会在总文本框中显示NaN如何避免它

 <script>
     function totalValue()
     {
          var a = document.getElementById("a").value;
          var b = document.getElementById("b").value;
          var c = document.getElementById("c").value;   
          var d = parseFloat(a)+ parseFloat(b)+ parseFloat(c);
          document.getElementById("total").value = d;
     }

 </script>

Answer 1

试试这个：

 <script>
     function totalValue()
     {
          var a = document.getElementById("a").value || 0;
          var b = document.getElementById("b").value || 0;
          var c = document.getElementById("c").value || 0;   
          var d = parseFloat(a)+ parseFloat(b)+ parseFloat(c);
          document.getElementById("total").value = d;
     }

 </script>

小提琴：http://jsfiddle.net/AvzwM/

Answer 2

您可以将0附加到字符串：

 <script>
     function totalValue()
     {
          var a = document.getElementById("a").value;
          var b = document.getElementById("b").value;
          var c = document.getElementById("c").value;   
          var d = parseFloat('0' + a)+ parseFloat('0' + b)+ parseFloat('0' + c);
          document.getElementById("total").value = d;
     }

 </script>

Answer 3

<script>
//checks if given text in text box is a number or unwanted string
filterInt = function (value)
{
if(/^\-?[0-9]+$/.test(value))
return Number(value);
return NaN;
}

 function totalValue()
 {
      var a = document.getElementById("a").value;
      var b = document.getElementById("b").value;
      var c = document.getElementById("c").value;   
      a=filterInt(a)||0; //if it is a string, convert it to a Nan and then if NaN,                  convert to zero
      b=filterInt(b)||0;
      c=filterInt(c)||0;
      var d = parseFloat(a)+ parseFloat(b)+ parseFloat(c);
      document.getElementById("total").value = d;
 }

如何在javascript中添加其他文本框值之前在文本框中避免使用NaN

3 个答案: