Can't add variables?

[Wayniac]

The problem that I am having is in the field "total", its spitting out "40.3180.4". Where it should be 117.95, below are my calculations.

 

quantity(10) * price(10) = subtotal(100)

subtotal(100) * 0.0795 = tax(7.95)

subtotal(100) * 0.1 = s&h(10)

subtotal(100) + tax(7.95) + s&h(10) = total(117.95)

 

<!-- Field Calculations -->
          <script>
		function f_sub_total(){
		 // Calculating Subtotal
		 var _quantity = document.getElementById("quantity").value;
		 if(!_quantity){
			var _quantity = 0;
		 }
		 var _price = document.getElementById("price").value;
		 if(!_price){
			var _price = 0;
		 }

		 document.getElementById("sub_total").value = _quantity * _price;

		 // Declare Local Variables
		 var _sub_total = document.getElementById("sub_total").value;

		 // Calculating Tax
		 document.getElementById("tax").value = _sub_total * 0.0795;

		 // Calculating S&H
		 document.getElementById("sh").value = _sub_total * 0.1;

		 // Declare Local Variables
		 var _tax = document.getElementById("tax").value;
		 var _sh = document.getElementById("sh").value;

		 // Calculating Total
		 document.getElementById("total").value = _sub_total + _tax + _sh;
		}
	  </script>

 

This is the Total outcome I get. Its adding the variables like strings. 100 + 7.95 + 10

 

Total: 1007.9510

 

PS: If you change the "+" signs to "*", they will multiply perfectly.

[F1Fan]

Because JS uses the + sign to add numbers and strings together, you need to explicitly tell JS that your variables are numbers. Use the parseInt() and parseFloat() functions on each of your numeric variables to "convert" them to what JS know is a number, not a string.

[Wayniac]

I tried this, but then all my JS code stopped working... clearly I made a mistake... Any suggestions for my syntax?

document.getElementById("total").value = parseFloat(“_sub_total + _tax + _sh”);

[F1Fan]

What you did basically just tried to do a parseFloat after the string addition. Try this:

 

document.getElementById("total").value = parseFloat(_sub_total) + parseFloat(_tax) + parseFloat(_sh);

 

For reference:

http://www.w3schools.com/jsref/jsref_parsefloat.asp

[Wayniac]

That worked perfectly, thank you very much.