checkboxes for multiple items

I am doing an interface where I want to list a bunch of things (index) and have a checkbox next to each of them. Then, using a button, edit or show all those selected items.
I am always running into this problem of checkboxes (maybe I am just stupid) so I spent some time and figured out a way that works for me. There are probably other solutions, but here is what I do:

First, in the index.html I have this javascript code:

<% content_for :javascript do %>
<script type="text/javascript" charset="utf-8">
/* <![CDATA[ */
    function editDevices() {
        var device_count = document.getElementsByName('device[]').length; 
        var total="";
        for(var i=0; i < device_count; i++){
            if(document.forms['group_edit'].elements['device[]'][i].checked) {
                if (total.length > 0) {
                    total += ","
                }
                total +=document.forms['group_edit'].elements['device[]'][i].value;
            }
        }

        new Ajax.Request('<%= group_edit_devices_path %>', { 
            parameters: { 
                authenticity_token: encodeURIComponent('<%=form_authenticity_token%>'),
                device_ids: total
            } 
        } 
        );
    }
    
    function showDevices() {
        var device_count = document.getElementsByName('device[]').length; 
        var total="";
        for(var i=0; i < device_count; i++){
            if(document.forms['group_edit'].elements['device[]'][i].checked) {
                if (total.length > 0) {
                    total += ","
                }
                total +=document.forms['group_edit'].elements['device[]'][i].value;
            }
        }

        new Ajax.Request('<%= group_show_devices_path %>', { 
            parameters: { 
                authenticity_token: encodeURIComponent('<%=form_authenticity_token%>'),
                device_ids: total
            } 
        } 
        );
    }
    /* ]]> */
</script>
<% end %>

Then I have the table of devices:

<table border="0" cellspacing="5" cellpadding="5">
    <thead>
        <tr>
            <th>&nbsp;</th>
            <th>Uid</th>
            <th>Name</th>
            <th>Ip</th>
            <th># Displays</th>
        </tr>
    </thead>
        <tfoot>
            <tr>
                <td colspan="5">
                    <ul class="tabs">
                        <li><%= link_to_function "Show", "showDevices()"  %></li>
                        <li><%= link_to_function "Edit", "editDevices()" %></li>
                        <li><%= link_to "Delete" %></li>
                    </ul>
                </td>
            </tr>
        </tfoot>
        <tbody>
            <% for device in @devices %>
            <tr>
                <td><%= check_box_tag("device[]", device.id, false, :id => "device_#{device.id}") %></td>
                <td><%=link_to_remote h(device.uid), :url => formatted_device_path(device, :js), :method => "get" %></td>
                <td><%=h device.name %></td>
                <td><%=h device.ip %></td>
                <td><%= device.displays.count %></td>
            </tr>
            <% end %>
        </tbody>
</table>

The result is that my ajax function will be called with a comma separated list of the ids of the selected devices.