OnBeforeUnload if qty inputs are differents of 0
<p>I have html table like this : </p>

<pre><code>&lt;table border="1"&gt;
  &lt;tr&gt;
    &lt;td&gt;Prod name &lt;/td&gt;
    &lt;td&gt;Qty&lt;/td&gt;
    &lt;td&gt;Add to cart &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
    &lt;td&gt;product 1 &lt;/td&gt;
    &lt;td&gt;&lt;input name="super_group[961]" type="text" class="input-text qty" title="Qty" value="0" size="5" maxlength="12"&gt;&lt;/td&gt;
    &lt;td&gt;&lt;input type="submit" name="Submit" value="Envoyer" /&gt;&lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
    &lt;td&gt;product 2 &lt;/td&gt;
    &lt;td&gt;&lt;input name="super_group[962]" type="text" class="input-text qty" title="Qty" value="0" size="5" maxlength="12"&gt;&lt;/td&gt;
    &lt;td&gt;&lt;input type="submit" name="Submit2" value="Envoyer" /&gt;&lt;/td&gt;
  &lt;/tr&gt;
&lt;/table&gt;
</code></pre>

<p>and I want to avoid that user quit the page when there is a quantity typed in the qty input fields.</p>

<p>(I have to show a message only if a quantity field is not 0).</p>
