javascript - Jquery 添加计算值

Question

我有一个表单，用户输入重量，其余字段自动计算。让一切正常工作，除了总计 - 它采用最后 2 个计算字段并将它们加在一起。表单加载后，我会在字段中得到 NaN。如有任何帮助，我们将不胜感激。

jQuery(function () {
  var min = 'Min';
  var total1 = .20;
  var total2 = .17;
  var total3 = .15;
  var total4 = .13;
  var total5 = .09;

  $('#weight').change(function () {
    var w = +$('#weight').val();
    var total;
    if (w < 425) {
      price = min;
    } else if (w < 1000) {
      price = total1;
    }
    else if (w < 2200) {
      price = total2;
    }
    else if (w < 4400) {
      price = total3;
    }
    else if (w < 11000) {
      price = total4;
    }
    else if (w > 11000) {
      price = total5;
    }        
    $('#rate').val(price);
  })
})

jQuery(function () {
  var min = 85.00;
  var total1 = .20;
  var total2 = .17;
  var total3 = .15;
  var total4 = .13;
  var total5 = .09;

  $('#weight').change(function () {
    var w = +$('#weight').val();
    var total;
    if (w < 425) {
      subtotal = min;
    } else if (w < 1000) {
      subtotal = w * total1;
    }
    else if (w < 2200) {
      subtotal = w * total2;
    }
    else if (w < 4400) {
      subtotal = w * total3;
    }
    else if (w < 11000) {
      subtotal = w * total4;
    }
    else if (w > 11000) {
      subtotal = w * total5;
    }        
    $('#subtotal').val(subtotal.toFixed(2));
  })
})

jQuery(function () {
  var iva = .16;

  $('#weight').change(function () {
    var s = +$('#subtotal').val();

    var total;
    if (s <= 85) {
      ivacalc = 85 * iva;
    } else if (s > 85) {
      ivacalc = s * iva;
    }
    $('#iva').val(ivacalc.toFixed(2));
  })
})

jQuery(function () {

  var a = parseFloat($('#subtotal').val());
  var b = parseFloat($('#iva').val());
  $('#total').val(a + b);
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div>
  <label for="weight">Total Weight (in lbs)</label>
  <input id="weight">
</div>
<div>
  <label for="rate">Rate Per Lb</label>
  <input id="rate">
</div>
<div>
  <label for="subtotal">Sub Total </label>
  <input id="subtotal">
</div>

<div>
  <label for="iva">IVA </label>
  <input id="iva">
</div>

<div>
  <label for="total">Total </label>
  <input id="total">
</div>

Answer 1

试试这个(假设您在字段中输入正确并且该功能被触发):

//Initialize variables and get values from the input field
var subtotal = $('#subtotal').val();
var iva = $('#iva').val();

//Assign to another variable
var a = parseFloat(subtotal);
var b = parseFloat(iva);
var total = a+b;
$('#total').val(total);