Node.compareDocumentPosition() - Web APIs 编辑
The Node.compareDocumentPosition() method reports the position of the given node relative to another node in any document — not just the given node’s document.
The return value is a bitmask of 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
Nodewith which to compare the firstnode’s document position.
Return value
An integer value whose bits represent the otherNode's relationship to the calling node.
More than one bit is set if multiple scenarios apply. For example, if otherNode is located earlier in the document and contains the node on which compareDocumentPosition() was called, then both the DOCUMENT_POSITION_CONTAINS and DOCUMENT_POSITION_PRECEDING bits would be set, producing a value of 10 (0x0A).
Example
const head = document.head;
const body = document.body;
if (head.compareDocumentPosition(body) & Node.DOCUMENT_POSITION_FOLLOWING) {
console.log('Well-formed document');
} else {
console.error('<head> is not before <body>');
}
Note: Because the result returned by compareDocumentPosition() is a bitmask, the bitwise AND operator must be used for meaningful results.
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
BCD tables only load in the browser
See also
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