ReplaceChild

:::info[Note] This is a point-in-time snapshot of the API documentation from January 2026. Going forward, we will not be maintaining a public copy of these references, and recommend users to refer to the built-in signature helpers available in the Hack LSP instead for complete and up-to-date information. :::

This function replaces the child oldnode with the passed new node

public function replaceChild<T as DOMNode>(
  DOMNode $newchildobj,
  DOMNode $oldchildobj,
): T;

If the new node is already a child it will not be added a second time. If the replacement succeeds the old node is returned.

Parameters

• DOMNode$newchildobj - The new node. It must be a member of the target document, i.e. created by one of the DOMDocument->createXXX() methods or imported in the document by DOMDocument::importNode.
• DOMNode$oldchildobj - The old node.

Returns

• mixed - - The old node or FALSE if an error occur.