Node.compareDocumentPosition()

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 otherNode's relationship to the calling Node 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

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`compareDocumentPosition`	Chrome Full support Yes	Edge Full support 12	Firefox Full support 9	IE Full support 9 Notes Full support 9 Notes Notes Only supports `contains` for elements	Opera Full support Yes	Safari Full support Yes	WebView Android Full support Yes	Chrome Android Full support Yes	Firefox Android Full support 9	Opera Android Full support Yes	Safari iOS Full support Yes	Samsung Internet Android Full support Yes

Legend

Full support: Full support
See implementation notes.: See implementation notes.