For a variety of reasons, you may need to get the owner document of a node. Some functions that operate on nodes are defined on the document object, and if you have a complex page with frames or i-frames, you will have multiple document objects (one for each frame). If you try to pass a node to a method on the wrong document object, your code will raise an exception.

The code

The code is fairly straightforward. The only tricky part is that Microsoft Internet Explorer 5 uses node.document instead of node.ownerDocument. And of course, the "owner" of a document is the document itself.

/**
 * Returns the owner document for a node
 * @param {Node} node The node to get the document for
 * @return {Document} The document owning the node
 */
goog.dom.getOwnerDocument = function(node) {
  // IE5 uses document instead of ownerDocument
  return node.nodeType == goog.dom.NodeType.DOCUMENT ? node :
      node.ownerDocument || node.document;
};

Further reading

• document object
• node.ownerDocument property
• node.document property