Get the number of elements inside another element

[salvi]

I'm working on an exercise I need to have finished pretty soon. The concept is simple: online bookstore with cart etc. It's written on php, using JS and mysql.

Each time I view a book's details, I can add it to my cart, where I can also alter it's quantity.
The code for my cart is this:

<div style="margin-left:20px;">
    <p><h3>Your list of books to buy:</h3></p>
<form id="place_order" action="Customer_Menu/plorder.php" method="post">
    <?php
    $cost = 0;
    if(isset($_SESSION['cart'])){
        foreach($_SESSION['cart'] as $cartLine){ ?>
            <span><b>Title:</b><input type="text" id="title" name="title" value="<?php echo $cartLine['title']; ?>" size="50" disabled="disabled" style="background-color:#666633;border:none;color:white;"/><br/>
        <b>Price:</b><input type="text" id="price" name="price" value="<?php echo $cartLine['price']; ?>" size="1" disabled="disabled" style="background-color:#666633;border:none;color:white;"/>$<br/>
                <b>Quantity:</b><select id="quant" onchange="javascript:ManageItem(this);">
            <option value="1">1</option>
            <option value="2">2</option>
            <option value="3">3</option>
        </select></span><hr/>
            <?php $cost += $cartLine['price']*$cartLine['quantity']; 
        }
    }
    ?> 
       Total Cost: <input type="text" id="total" name="total" size="1" value="" style="background-color:#666633;border:none;color:white;" disabled="disabled"/>$<br/>
    <input type="submit" id="order_btn" name="order_btn" value="Procceed to order!"/>
</form>
</div>

As you can see, each time I choose a book to add it to my cart, a new span will be created, to hold the info of this book. What I need to do with the ManageItem js function, is to update the total cost at the bottom of the page, but I can't seem to be getting anywhere, so any help will be mostly appreciated.

Here is what I've done so far:

function ManageItem(x){
	var my_spans = document.getElementsByTagName("span");
	var my_prices = new Array();
	var my_quantity = new Array();
	var total = 0;

	for(var i=0;i<my_spans.length;i++){
		//working with each span seperate
		var this_span = my_spans[i].childNodes;

		my_quantity[i] = x.selectedIndex.value;
		my_prices[i] = parseInt(this_span.document.getElementById("price").value)*parseInt(my_quantity[i]);
	}
	for(var j=0;j<my_prices.length;j++){
		total +=my_prices[j]; 
	}
	document.getElementById("total").value = total;
	
}

[salvi]

Changed my JS code to this:

function ManageItem(){
	var my_spans = document.getElementsByTagName("span");
	var this_span = new Array();
	var my_prices = new Array();
	var my_quantity = new Array();
	var total = 0;

	for(var i=0;i<my_spans.length;i++){
		this_span[i] = my_spans[i].getElementsByTagName("*");
		for(var j=0;j<this_span[i].length;j++){
			my_quantity[i] = this_span[i].item(2).selectedIndex.value;
			my_prices[i] = parseInt(this_span[i].item(1).value)*parseInt(my_quantity[i]);
		}
	}
	for(var j=0;j<my_prices.length;j++){
		total +=parseInt(my_prices[j]); 
	}
	document.getElementById("total").value = total;
}

But if i try to print my my_quantity[i] to check if the value is assigned correctly, I'm getting "undefined" :/

[JunkMale]

What you might want to do is use a <textarea> to store your cart information.

[salvi]

Wouldn't that be the same as using span?
Each time I add a product, the page looks like that http://img341.imageshack.us/img341/6369/siteej.jpg

[Kor]

For the beginning I see a mistake: you create, in a PHP loop, elements which have the same id (id="title", id="price"...). Unlike the name attribute, the id must be an unique identifier on the same document/session.