Calculating checkbox totals with jQuery
<p>I am trying to create a page total based on options selected from checkboxes.</p>

<p>here is my HTML markup:</p>

<pre><code>&lt;input type="checkbox" id="option1" name="option1" value="&lt;?= $add[0] ?&gt;" /&gt;t1 + &amp;pound;&lt;?= $add[0] ?&gt;&lt;br /&gt;
&lt;input type="checkbox" id="option2" name="option2" value="&lt;?= $add[1] ?&gt;" /t2 + &amp;pound;&lt;?= $add[1] ?&gt;&lt;br /&gt;
&lt;input type="checkbox" id="option3" name="option3" value="&lt;?= $add[2] ?&gt;" /&gt;t3 + &amp;pound;&lt;?= $add[2] ?&gt;&lt;br /&gt;
&lt;input type="checkbox" id="option4" name="option4" value="&lt;?= $add[3] ?&gt;" /&gt;t4 + &amp;pound;&lt;?= $add[3] ?&gt; &lt;br /&gt;
</code></pre>

<p>This is my JavaScript that doesn't work:</p>

<pre><code>var option1 = 0;
var option2 = 0;
var option3 = 0;
var option4 = 0;
var op = 0;

var extra = document.getElementById('extra');

$(":input").change(function()
{

    option1 = $("input[name=option1]:checked").attr("value");
    option2 = $("input[name=option2]:checked").attr("value");
    option3 = $("input[name=option3]:checked").attr("value");
    option4 = $("input[name=option4]:checked").attr("value");

    op = parseInt(option1) + parseInt(option2) + parseInt(option3) + parseInt(option4) ;

    extra.innerHTML = '&lt;p&gt;&amp;pound;'+op+'&lt;/p&gt;';
});
</code></pre>

<p>Have I gone wrong somewhere?
I have other totals working, have removed from script so it's easier to read, just this one doesn't work!</p>

<p>EDITED:</p>

<pre><code>&lt;input id="option1" name="option1" value="20" type="checkbox"&gt;t1 + £20&lt;br&gt;
&lt;input id="option2" name="option2" value="20" type="checkbox"&gt;t2 + £20&lt;br&gt;
&lt;input id="option3" name="option3" value="20" type="checkbox"&gt;t3 + £20&lt;br&gt;
&lt;input id="option4" name="option4" value="20" type="checkbox"&gt;t4 + £20 &lt;br&gt;
</code></pre>

<p>ADDED RADIO:</p>

<pre><code>    &lt;input id="delivery" name="delivery" value="0" checked="checked" type="radio"&gt; Standard (72hrs) - no addtional charges&lt;br&gt;
                    &lt;input id="delivery" name="delivery" value="200" type="radio"&gt; 45hrs - £200 per email templates&lt;br&gt;
                    &lt;input id="delivery" name="delivery" value="250" type="radio"&gt; 24hrs - £250 per email templates&lt;br&gt;
</code></pre>
