Programmer's Guide > Interfaces > W3C Node interface > insertBefore method
  
insertBefore method
Inserts the node newChild before the existing child node refChild. If refChild is null, insert newChild at the end of the list of children.
If newChild is a DocumentFragment object, all of its children are inserted, in the same order, before refChild. If the newChild is already in the tree, it is first removed.
insertBefore(newChild [, refChild] )
Parameters
NodenewChild
The node to insert.
NoderefChild
[optional] The reference node, i.e., the node before which the new node must be inserted.
Returns
Node. The node being inserted.
Throws
DOMException
HIERARCHY_REQUEST_ERR: Raised if this node is of a type that does not allow children of the type of the newChild node, or if the node to insert is one of this node's ancestors.
WRONG_DOCUMENT_ERR: Raised if newChild was created from a different document than the one that created this node.
NO_MODIFICATION_ALLOWED_ERR: Raised if this node is readonly or if the parent of the node being inserted is readonly.
NOT_FOUND_ERR: Raised if refChild is not a child of this node.