How can I add a child to a node at a specific position?
You can use NodeSet#before like this:
node.children.before(span_node)NodeSet#before is a short-cut method to insert an item as the first element. A more general-purpose solution is to use Node#before and Node#after. For example, some_node.before foo will add the node foo as the sibling directly before some_node. Node#after is similar. Note that this:
node.children.first.before(span_node)is thus equivalent to the solution above.