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

let 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 that the first statement above uses the NodeList.item() method with a parameter value of 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

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidEdge MobileFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
Basic supportChrome Full support YesEdge Full support YesFirefox Full support 9IE Full support 5
Notes
Full support 5
Notes
Notes Only supports contains for elements
Opera Full support YesSafari Full support YesWebView Android Full support YesChrome Android Full support YesEdge Mobile Full support YesFirefox Android Full support 9Opera Android Full support YesSafari iOS Full support YesSamsung Internet Android ?

Legend

Full support  
Full support
Compatibility unknown  
Compatibility unknown
See implementation notes.
See implementation notes.

See also