Subtracting discount on order form?

JavaScript
1

Hello,

I have a custom order form that will add up and show the total but I’m having trouble getting it to subtract the discount. What changes do I need to make to my javascript?

The form is here:
http://www.houston-reviews.com/purchase/order.php

This is the javascript I’m using which is also viewable in the source code of the above form:


<script language="JavaScript" type="text/javascript"> 
<!--
 
/* This script is Copyright (c) Paul McFedries and 
Logophilia Limited (http://www.mcfedries.com/).
Permission is granted to use this script as long as 
this Copyright notice remains in place.*/
 
function CalculateTotal(frm) {
	
    var order_total = 0
//	var order_disc = 0
    // Run through all the form fields
    for (var i=0; i < frm.elements.length; ++i) {
 
        // Get the current field
        form_field = frm.elements[i]
 
        // Get the field's name
        form_name = form_field.name
		
		
		
		/*
		        // Is it a "discount" field?
        if (form_name.substring(0,4) == "DISC") {
 
            // If so, extract the price from the name
            item_price2 = parseFloat(form_name.substring(form_name.lastIndexOf("_") + 1))
 
            // Get the quantity
            item_quantity2 = parseInt(form_field.value)
 
            // Update the order total
            if (item_quantity2 >= 0) {
				var order_disc
               order_disc += item_quantity2 * item_price2
				//alert(order_disc)
            }
        }
		
		*/
		
		
		
		
 
        // Is it a "product" field?
        if (form_name.substring(0,4) == "PROD") {
 
            // If so, extract the price from the name
            item_price = parseFloat(form_name.substring(form_name.lastIndexOf("_") + 1))
 
            // Get the quantity
            item_quantity = parseInt(form_field.value)
 
            // Update the order total
            if (item_quantity >= 0) {
				
                order_total += item_quantity * item_price
           }
        }
    }
 
    // Display the total rounded to two decimal places
    frm.TOTAL.value = round_decimals(order_total, 2)
	frm.amount.value = round_decimals(order_total, 2)
 
}
 
function round_decimals(original_number, decimals) {
    var result1 = original_number * Math.pow(10, decimals)
    var result2 = Math.round(result1)
    var result3 = result2 / Math.pow(10, decimals)
    return pad_with_zeros(result3, decimals)
}
 
function pad_with_zeros(rounded_value, decimal_places) {
 
    // Convert the number to a string
    var value_string = rounded_value.toString()
    
    // Locate the decimal point
    var decimal_location = value_string.indexOf(".")
 
    // Is there a decimal point?
    if (decimal_location == -1) {
        
        // If no, then all decimal places will be padded with 0s
        decimal_part_length = 0
        
        // If decimal_places is greater than zero, tack on a decimal point
        value_string += decimal_places > 0 ? "." : ""
    }
    else {
 
        // If yes, then only the extra decimal places will be padded with 0s
        decimal_part_length = value_string.length - decimal_location - 1
    }
    
    // Calculate the number of decimal places that need to be padded with 0s
    var pad_total = decimal_places - decimal_part_length
    
    if (pad_total > 0) {
        
        // Pad the string with 0s
        for (var counter = 1; counter <= pad_total; counter++) 
            value_string += "0"
        }
    return value_string
}
 
//-->
</script>

Thanks in advance!

Tim

2

Where in the form is the discount specified? Are they the SuppYo credits?

If so, the field name would need to start with DISC for the script to interpret it appropriately, due to this:

if (form_name.substring(0,4) == "DISC") {
3

Hi,

Yes, the discount being applied is the Suppyo Credits. The if loop with the “DISC” is a loop I added to the javascript. I also had renamed the field to DISC. It didn’t work so I commented it out and changed the field name back.

The DISC loop isn’t working. Any ideas on how to accomplish the subtraction of the Suppyo Credit?

Thanks for your input,

Tim

4

I suggest that you uncomment the discount code and rename the field again, so that we can look investigate the page and determine what more will be needed to get things working properly.

5

I uncommented the discount code and renamed the field name.
http://www.houston-reviews.com/purchase/order.php

Thanks,

Tim

6

Here is how your existing discount code gets the order_disc value:


// If so, extract the price from the name
item_price2 = parseFloat(form_name.substring(form_name.lastIndexOf("_") + 1))
// Get the quantity
item_quantity2 = parseInt(form_field.value)
// Update the order total
if (item_quantity2 >= 0) {
    var order_disc
    order_disc += item_quantity2 * item_price2
}

You don’t need to bother with the price or quantity. You can get the discount amount straight from the select field, replacing all of the above with:


// If so, extract the price from the select field
order_disc += Number(form_field.value);
7

Thank you for your help Paul!

I made the change you suggested but the total value doesn’t update?

Thanks,

Tim

8

I’m not testing the code locally elsewhere, so we’re going to go through this step by step on your own server so that you know what’s happening with troubleshooting this too.

It looks like the code requires the discount to be placed before the item quantity.

You can either update the HTML form so that the discount occurs before the quantity, or you can do the more time consuming task of updating the script, so that the order of things is less important.

Which one will you do?

9

Excellent! I changed the order in the html form and now it’s working. I know PHP but not javascript but I’ll try and figure out how to edit the script so the order doesn’t matter.

Thank you so much!!! I’ve spent many hours on this!

Tim