DOMNode::insertBefore — Adds a new child before a reference node
This function inserts a new node right before the reference node. If you plan to do further modifications on the appended child you must use the returned node.
The new node.
The reference node. If not supplied,
newnode is appended to the children.
The inserted node.
Raised if this node is readonly or if the previous parent of the node being inserted is readonly.
Raised if this node is of a type that does not allow children of the type of the
newnode node, or if the node to append is one of this node's ancestors or this node itself.
newnode was created from a different document than the one that created this node.
refnode is not a child of this node.