Here's an example using css to select appropriate script line element:

```
<div class="jubjub-view-script">
<table>
<thead>
<tr class=""></tr>
</thead>
<tbody>
<tr class="jubjub-view-script-line"></tr>
<tr class="jubjub-view-script-line"></tr>
<tr class="jubjub-view-script-line"></tr>
<tr class="jubjub-view-script-line"></tr>
</tbody>
</table>
</div>

var $container = $('div.jubjub-view-script');
var $line = $container.find('tr.jubjub-view-script-line:eq(3)');
```