compareDocumentPosition

Summary

Compares the position of two nodes in a document.

Syntax

var positionBitmask = node.compareDocumentPosition(/* see parameter list */);

Parameters

otherNode

Data-type: DOM Node

The node to be compared to the reference node, which is the node executing the method.

Return Value

Returns an object of type NumberNumber

Describes how the position of the node specified by the otherNode parameter relates to the position of the reference node. The return value contains one or more of the following flag values:

Node constant name	Return value (Integer)	Return value (Hexadecimal)	Description
DOCUMENT_POSITION_DISCONNECTED	1	0x01	The nodes are disconnected.
DOCUMENT_POSITION_PRECEDING	2	0x02	The position of the node specified by the otherNode parameter precedes the position of the reference node.
DOCUMENT_POSITION_FOLLOWING	4	0x04	The position of the node specified by the otherNode parameter follows the position of the reference node.
DOCUMENT_POSITION_CONTAINS	8	0x08	The reference node contains the node specified by the otherNode parameter.
DOCUMENT_POSITION_CONTAINED_BY	16	0x10	The node specified by the otherNode parameter contains the reference node.
DOCUMENT_POSITION_IMPLEMENTATION_SPECIFIC	32	0x20	The node positions depend on the DOM implementation and cannot be compared.

Examples

This example determines if the web document is incorrectly marked up with the body element before the head element. Note: Web browsers sometimes self correct markup errors. HTML5 is the first specification to give guidelines to browser vendors on how they should correct markup errors.

var head = document.getElementsByTagName('head').item(0);
if (head.compareDocumentPosition(document.body) & Node.DOCUMENT_POSITION_FOLLOWING) {
  console.log("well-formed document");
} else {
  console.log("<head> is not before <body>");
}

Notes

For information about the factors that affect the position of nodes within the DOM, see the related specifications.

Related specifications

DOM Level 3 Core: Recommendation

Attributions

Mozilla Developer Network : [Node.compareDocumentPosition Article]
Microsoft Developer Network: [compareDocumentPosition Method Article]