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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

compareMask = node.compareDocumentPosition(otherNode)

Parameters

otherNode: The other Node with which to compare document positioning.

Return value

An integer value whose bits represent the calling Node's relationship to otherNode within the Document. More than one of the bits may be set, if multiple scenarios apply. If otherNode is located earlier in the document and also contains the Node on which compareDocumentPosition() was called, then the DOCUMENT_POSITION_CONTAINS and DOCUMENT_POSITION_PRECEDING bits would be set, resulting in a value of 0x0A or decimal 10.

Example

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 bycompareDocumentPosition 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.	Obsolete	Initial definition

Browser compatibilityUpdate compatibility data on GitHub

	Desktop
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari
Basic support	Yes	Yes	9	5 5 Only supports `contains` for elements	Yes	Yes

	Mobile
	Android webview	Chrome for Android	Edge Mobile	Firefox for Android	Opera for Android	iOS Safari	Samsung Internet
Basic support	Yes	Yes	Yes	9	Yes	Yes	?