Question

So I’m working on an order form, where people can select different quantities of items, and it then uses JS to calculate to the totals. So for example you can select 2 Brown hats ($15 each) and the TOTAL automatically becomes $30. In the POST page I can then pull the name of the text box and know they ordered 2 brown hats.

Here is my problem: I want to set up a radio button option that will allow them to select one item only, and have it add to that final total here is what it looks like:

<input type="radio" value="0" name="Syllabus" checked="No" /> Paper ($0)<br />

<input type="radio" value="0" name="Syllabus" checked="No" /> USB ($0)<br />

<input type="radio" value="20" name="Syllabus" checked="No" /> Both ($20)<br />

So how can I use JS to add $20 to the total if “BOTH” is selected? And then of course $20 is removed if they select one of the other options. And finally, if they do select PAPER or USB, how do I know in the final output what they selected, since the value will be 0 either way?

Thanks for the help!

—— IF IT HELPS ANYONE HERE IS THE CODE I USE TO ADD THE VALUES OF THE OTHER TEXT BOXES, I THEN PAD THE TOTAL WITH ZEROS AND ROUND IT ——

// JavaScript Document

    function CalculateTotal(frm) {
    var order_total = 0

    var syllabuscost;

    var radios = document.getElementsByTagName('input');
    var radiovalue;
    for (var z = 0; z < radios.length; z++) {
        if (radios[z].type === 'radio' && radios[z].checked) {
            // get value, set checked flag or do whatever you need to
            radiovalue = radios[z].value; 

            //Change the syllabus cost depending on the value of the radio button
            if (radiovalue == "Paper" || radiovalue == "USB") {
                syllabuscost = 0
            }
            else if (radiovalue == "Both") {
                syllabuscost = 20
            }      
        }
    }

    // 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 "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 Also added the syllabuscost to the total price!
    frm.TOTAL.value = round_decimals(order_total+syllabuscost, 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
}

AND THE HTML

<form>
<tr>
<th><label for="PROD_BrownShoe_175">Brown Shoe</label></th>
<td><input type="text" name="PROD_BrownShoe_175" onchange="CalculateTotal(this.form)" /> ($175) - Each</td>
</tr>
<tr>
<th><label for="PROD_BlackShoe_255">Black Shoe</label></th>
<td><input type="text" name="PROD_BlackShoe_255" onchange="CalculateTotal(this.form)" /> ($255) - Each</td>
</tr>
<tr>
<th><label for="PROD_BlueShoe_325">Blue Shoe</label></th>
<td><input type="text" name="PROD_BlueShoe_325" onchange="CalculateTotal(this.form)" /> ($325) - Each</td>
</tr>
<tr>
<th>Total $:</th>
<td><input type="text" name="TOTAL" onFocus="this.form.elements[0].focus()" /></td>
</tr>
</form>

Answer 1

Ok actually I went a different route and solved the problem. I’ve set it up so it just goes through ALL the radio buttons on the page, and then added a snippet that changes the syllabus cost depending on if it finds the value “paper”, “usb”, or “both”.

This allows me to scale this whole thing up, should I need to add more radio buttons with the same type of functionality.

There might be a cleaner, more efficient way to do this, but this is the best I could come up with. The responses I got helped a little, but didn’t really help solve the problem. Hope this helps someone else.