Node.compareDocumentPosition()

The Node.compareDocumentPosition() method compares the position of the current node against another node in any other document.

The return value is a bitmask with the following values:

Name	Value
`DOCUMENT_POSITION_DISCONNECTED`	1
`DOCUMENT_POSITION_PRECEDING`	2
`DOCUMENT_POSITION_FOLLOWING`	4
`DOCUMENT_POSITION_CONTAINS`	8
`DOCUMENT_POSITION_CONTAINED_BY`	16
`DOCUMENT_POSITION_IMPLEMENTATION_SPECIFIC`	32

Syntax

JavaScript

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node.compareDocumentPosition( otherNode )

Example

JavaScript

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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>");
}

Note: Because the result returned by compareDocumentPosition is a bitmask, the bitwise and operator has to be used for meaningful results.

Note: First statement uses NodeList method item(0), which is equivalent to getElementsByTagName('head')[0].

Specifications

Specification	Status	Comment
DOM The definition of 'Node.compareDocumentPosition()' in that specification.	Living Standard
Document Object Model (DOM) Level 3 Core Specification The definition of 'Node.compareDocumentPosition()' in that specification.	Recommendation	Initial definition

Feature	Chrome	Firefox (Gecko)	Internet Explorer	Opera	Safari
Basic support	(Yes)	(Yes)	9.0	(Yes)	(Yes)

Feature	Android	Firefox Mobile (Gecko)	IE Mobile	Opera Mobile	Safari Mobile
Basic support	(Yes)	(Yes)	?	(Yes)	(Yes)

License

© 2016 Mozilla Contributors
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-us/docs/web/api/node/comparedocumentposition

API DOM Method Node