insertAfter

jQuery insertAfter(jQuery/list/object source, jQuery/list target)
Inserts a node after a specific node.
If an existing node is passed as the source, it is being moved after the given node.
The target node must exist and be fully-expanded.

Returns the newly-inserted node.

<ul id="treeview">
    <li>My Project
        <ul>
            <li id="someid">js</li>
            <li>css</li>
        </ul>
        <li>index.html<li>
        <li>upload.php<li>
    </li>
</ul>

<script type="text/javascript">
    jQuery(function ($) {
        var treeview = $("#treeview").shieldTreeView().swidget();

        treeview.insertAfter({text: "new item"}, $("#someid"));
    });
</script>