Field Calculations

[Wayniac]

I am trying to get the quantity to multiply with the price and to equal the sub_total. The problem is getting it to instantly calculate with the field. So as soon as the user enters in the price and quantity, I want the sub_total to instantantly calculate. I was thinking of setting up a function and an onClick for the sub_total. I just can't seem to get it to work, nothing is changing so I am clearly missing a step.

 

$quantity = mysql_real_escape_string(stripslashes($_POST['quantity']));
  
$price = mysql_real_escape_string(stripslashes($_POST['price']));

$sub_total = mysql_real_escape_string(stripslashes($_POST['sub_total']));

 

I placed these quick variables in to see if the fields would even accept any values.

 

$price = 2.99;
$quantity = 100;	  
$sub_total = $quantity * $price;

 

Here are the fields...

<input name="quantity" id="quantity" size="35" maxlength="255" />
<input name="price" id="price" size="35" maxlength="255" />
<input name="sub_total" id="sub_total" size="35" maxlength="255" />

 

Any suggestions would be greatly appreciated...

[Domcsore]

PHP is server side, there for to do this you will need to use a form and use post or get method linking to a different page. Alternatively look up AJAX. I think I am right in what you mean. 

[Wayniac]

Sorry Dom, not sure I follow on the first part.

[Pikachu2000]

PHP is parsed on the server, not on the client machine. You need a client-side technology to do what you're trying to do.

[havenpets]

You need javascript for this, not PHP.

 

Javascript can grab the value of one input and multiply it to another to equal another value of a different input. If that makes sense...

[havenpets]

<script>
function sub_total(){
qty = document.getElementById('quantity').value;
if(!qty){
    qty = 0;
}
price = document.getElementById('price').value;
if(!price){
    price = 0;
}
document.getElementById('sub_total').value = qty * price;
}
</script>

<input name="quantity" id="quantity" size="35" maxlength="255" onkeyup="sub_total();" />
<input name="price" id="price" size="35" maxlength="255" onkeyup="sub_total();" />
<input name="sub_total" id="sub_total" size="35" maxlength="255" />

 

Works like a charm. Enjoy

[Wayniac]

Thank you both for your replies.

 

havenpets, I tried that code but nothing worked, I even tried changing it to an onClick, but no go...

[havenpets]

Whoops sorry, I forgot IE is a little fussy.

 

Works more than a charm now

<script>
function sub_total(){
var qty = document.getElementById('quantity').value;
if(!qty){
    var qty = 0;
}
var price = document.getElementById('price').value;
if(!price){
    var price = 0;
}
document.getElementById('sub_total').value = qty * price;
}
</script>

<input name="quantity" id="quantity" size="35" maxlength="255" onkeyup="sub_total();" />
<input name="price" id="price" size="35" maxlength="255" onkeyup="sub_total();" />
<input name="sub_total" id="sub_total" size="35" maxlength="255" />

[Wayniac]

Thank you heaven, unfortunately I could'nt get that to work either. Should I be putting the script in the header? Everything seems like it should work but nothing at all is happening...

[havenpets]

http://havenpets.tridiantgames.com/test/jstest.php - Example

 

It's working fine on Firefox, Internet Explorer and Google Chrome... Take a look for yourself.

[Wayniac]

Yes your right. You can't imagine how much I appreciate you going through the effort to do that for me. I will keep this forum updated when I figure out what my mistake is.

[Wayniac]

Thank you so much havenpets! I got your code working, the issue I was having was putting the Javascript within the form. I placed it outside and worked marvously. Once again, thank you so much