Sending a URL to server with JavaScript

Question

I am not a great programmer and would like help.

The javascript code below is supposed to send the url in the format /update/1/3 to my django test server to update an item. However when I try, I only see a post of /update/ in the console log.

<script type="text/javascript">
    function goTo()
    {
        var url = '/update';
        var quantity = document.forms[0].quantity.value;
        var menuitem_id = document.forms[0].menuitem_id.value;
        window.location = url+'/'+menuitem_id+'/'+quantity;
        return false;
    }
</script>

What am I doing wrong?

As requested, please see the HTML:

<div class="container">
<td class="table">
    <form method="post" action="." onsubmit="return goTo()">
    <div>
    {% csrf_token %}
        {% if item %}
        <label for="quantity">How much {{ item.product.name }} from {{ item.product.restaurant.name }} do you want?</label>
        <input style="height:25px;font-size:12pt;" type="text" name="quantity" value="{{ item.quantity }}" id="quantity" size="2" class="quantity" maxlength="5"/>
        <input type="hidden" name="menuitem_id" value="{{ item.product.id }}" id="menuitem_id"/>
        </td>
        <td>
        {% endif %}
    </div>
    <button class="btn btn-primary" type="submit">Update</button>
    </form>
</td>
</div>

Answer 1

The code you posted looks fine. Make sure "quantity" and "menuitem_id" are the names (not the ids) of the inputs in the first form on the page (forms[0]). Many times, for example, people forget that the search bar at the top of their page is technically the first form.

Also, if these inputs are user-specified and you're anticipating them to always be numbers, it may also help to clean out any unwanted characters with something like:

var quantity = document.forms[0].quantity.value.replace(/[^0-9]/g,'');

..which will remove any non-numeric characters from the input. This will prevent whitespace from mucking up the URL path and also help (a little bit) to protect your users from javascript injection attacks.