prototype: loop with each and select childs by classname - prototypejs

Question

I have following structure:
html structure:
<table class="structure">
<tr>
<td class="id">
<div class="product-id">123</div>
</td>
<td class="article">
<ul name="attribute[151]">
<li class="active"> A</li>
<li>B</li>
</ul>
</td>
</tr>
<tr>
<td class="id">
<div class="product-id">456</div>
</td>
<td class="article">
<ul name="attribute[151]">
<li class="active"> A</li>
<li>B</li>
</ul>
</td>
</tr>
</table>
I want to loop every tr element to get the li element with class active. I pick tr because i also want to select the product-id.
how can i select a css selector inside my each loop?
prototype:
$$('.structure tr').each(
function (index) {
//wrong
console.log(index.down(".article li.active a'").readAttribute('rel'));
}
);
}

Answer 1

So you can simplify your javascript like this
$$('.structure tr').each(
function (index) {
console.log(index.down('li.active a').readAttribute('rel'));
//wrong
console.log(index.down(".article li.active a'").readAttribute('rel'));
// extra single quote ^^^^
}
);
}
You also have an extra single quote (') in the down() method which might be confusing the CSS selector engine (which is Sizzle)