jQuery Addition

Question

I'm attempting to add 2 values together with jQuery. I have a table with these values:

<table>
<tr id="fc_cart_foot_subtotal">
<td class="fc_col2">$7.95</td>
</tr>
<tr id="fc_cart_foot_shipping">
<td class="fc_col2">$4.00</td>
</tr>
<tr id="fc_cart_foot_total">
<td class="fc_col2">$7.95</td>
</tr>
</table>

I need to add the value of #fc_cart_foot_subtotal .fc_col2:

<tr id="fc_cart_foot_subtotal">
<td class="fc_col2">$7.95</td>
</tr>

to the value of #fc_cart_foot_shipping .fc_col2:

<tr id="fc_cart_foot_shipping">
<td class="fc_col2">$4.00</td>
</tr>

and have the value of #fc_cart_foot_total .fc_col2 updated

<tr id="fc_cart_foot_total">
<td class="fc_col2">$7.95</td>
</tr>

So in this example, the first subtotal value of $7.95 should add $4.00 to give a total of $11.95. The subtotal and shipping cost will change, so I'll need to be able to "grab" those values as they change and use them in an equation.

Answer 1

To convert the dollar string into a number for addition:

function parseDollar(str) {
   return +str.substr(1);
}

Then to add the numbers together and format it correctly:

$('#fc_cart_foot_total .fc_col2').text('$' + (
    parseDollar($('#fc_cart_foot_subtotal .fc_col2').text()) +
    parseDollar($('#fc_cart_foot_shipping .fc_col2').text())
).toFixed(2));

If it is possible that you can get negative dollar values e.g. "-$1.00", then change parseDollar to:

function parseDollar(str) {
    return +str.replace(/\$/, '');
}