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 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.
Obsolete Initial definition

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support Yes Yes951 Yes Yes
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support Yes Yes Yes9 Yes Yes ?

1. Only supports contains for elements

See also