Using Javascript To Subtract Dynamically Generated Numbers

javascript subtract

[kankles]

Hi,

I'm promoting a buy $500 in product get free shipping offer. I'd like to add a custom message that subtracts a dynamically generated subtotal number from $500.

IE. Add $430 to your cart to get free shipping.

If it helps, the subtotal is wrapped in the following tags:

 <p class="subtotal">
   <label>Subtotal:</label> $70.00
  </p>

[MichaelBluejay]

Can you put the subtotal into an <input type=hidden> field? Then it will be easy to work with.

<script type=text/javascript>
theSubTotal = document.getElementById('subtotal').value-0;
remainder = 500-theSubTotal;
</script>

<input type=hidden id="subtotal" value="70.00">

Note that I subtract 0 from the value. That's standard practice to make sure when you get a number value that JS treats it like a number and not like a string.