insertBefore method

Node insertBefore(
  1. Node node,
  2. Node? child
)

The insertBefore() method of the Node interface inserts a node before a reference node as a child of a specified parent node.

If the given node already exists in the document, insertBefore() moves it from its current position to the new position. (That is, it will automatically be removed from its existing parent before appending it to the specified new parent.)

This means that a node cannot be in two locations of the document simultaneously.

Note: The Node.cloneNode can be used to make a copy of the node before appending it under the new parent. Note that the copies made with cloneNode() will not be automatically kept in sync.

If the given child is a DocumentFragment, the entire contents of the DocumentFragment are moved into the child list of the specified parent node.

Implementation

external Node insertBefore(
  Node node,
  Node? child,
);