Why keeps sum returning a false value

Question

I have some input values inside a form like this:

<tr>
  <td>
      <input type="text" disabled class="qty" value="1" name="quantity">
  </td>
  <td>
    <span class="euro">€</span><input type="text" disabled class="price" value="0,60">
  </td>
</tr>
<tr>
  <td>
      <input type="text" disabled class="qty" value="1" name="quantity">
  </td>
  <td>
    <span class="euro">€</span><input type="text" disabled class="price" value="0,25">
  </td>
</tr>
// below table row is empty because product is not on stock! //
<tr>
  <td></td>
  <td></td>
</tr>
//etc...

I try to sum the qty and price input values but my script keeps returning NaN as result. I think it is because when a product is not on stock the table cells are empty. Therefore returning NaN or undefined. I've read numerous threads like this but that doesn't fix my problem.

What I have is this:

function update_amounts(){
  var sum = 0.0;
  $('#inspiration .table tbody tr').each(function() {
    var qty = $(this).find('.qty').val();
    var price = $(this).find('.price').val();
    console.log(price, qty);
    var amount = (qty*price)
        sum+=amount;
  });
  $('.total').text(sum);    
}

What I already tried is this:

var qty = parseInt($(this).find('.qty').val()) || 0;
var price = parseFloat($(this).find('.price').val()) || 0;

And:

var qty = $(this).find('.qty').val();
var price = $(this).find('.price').val();
qty= parseInt(qty) || 0;
price= parseFloat(price) || 0;
console.log returns

    (2) 1 0
        0 0
    (3) 1 0

Below is what console.log returns for the original code (first one is price, second qty):

0,60 1
0,90 1
undefined undefined
0,14 1
0,12 1
0,75 1

I don't know any new option to get this fixed!

Your code works on my side, with the `|| 0`. Perhaps you had a caching issue? — Evan Knowles, Aug 29 '14 at 11:21
@JaapVermoolen: And the `log` calls? `parseInt`/`parseFloat` never return `undefined`. — Bergi, Aug 29 '14 at 11:21

Quentin · Accepted Answer · 2014-08-29T11:26:12.487

1

You need to use the . character to start the floating point, not ,.

value="0,60" will not be treated as a number. value="0.60" will be.

%  node
> "0.60" * 5
3
> "0,60" * 5
NaN
>

When run through parseFloat, it will hit the , and stop treating the rest as a number, so you end up with 0.

> parseFloat("0.60") * 5
3
> parseFloat("0,60") * 5
0

edited Aug 29 '14 at 11:26

answered Aug 29 '14 at 11:20

Quentin

914,110
126
1,211
1,335

1

What exactly do you mean? – Meules Aug 29 '14 at 11:22
@JaapVermoolen price should be `0.60`, not `0,60`. – Barmar Aug 29 '14 at 11:22
@JaapVermoolen — I've added an example to the answer. – Quentin Aug 29 '14 at 11:23
`0,60` will be treated as a number, but the number will be `0` because it stops parsing when it hits the `,`. – Barmar Aug 29 '14 at 11:23
@Barmar — If it was JavaScript code then the `,` would be treated as a comma operator (so it wouldn't stop parsing per se), but it isn't JavaScript. It is a string pulled out of the DOM. – Quentin Aug 29 '14 at 11:24
@Quentin `parseFloat("0,60")` => `0`. – Barmar Aug 29 '14 at 11:24
@Barmar — Ah. I was looking at the original code rather than the selection of non-working attempts to fix it. – Quentin Aug 29 '14 at 11:25
Conversely, I didn't notice that the original didn't have parseFloat. – Barmar Aug 29 '14 at 11:26
@Quentin: Thx! Excellent... Never thought of that because the system pulls the price out of a Twig template. Therefore uses a comma instead of a point. – Meules Aug 29 '14 at 11:28

Why keeps sum returning a false value

1 Answers1