XPath

dom. XPath

Source:

XPath utility functions.

Example

Print all entries in a FreeDict dictionary.

var dictXML = <parsed XML document>;// Parsing omitted in this example.
var xpath = dom.XPath.new(dictXML, {
    "tei": "http://www.tei-c.org/ns/1.0"
});
var iter = xpath('tei:TEI/tei:text/tei:body/tei:entry').iter(dictXML);
var formXPath = xpath('tei:form');
var orthXPath = xpath('tei:orth');
var pronXPath = xpath('tei:pron');
var defXPath  = xpath('tei:sense/tei:cit/tei:quote|tei:sense/tei:def');
dom.iterateAsync(iter, function forEach(entryElement) {
    var iter = formXPath.iter(entryElement);
    while ((element = iter.iterateNext())) {
        console.log(orthXPath.str(element),
                    pronXPath.str(element), ':');
    }
    iter = defXPath.iter(entryElement);
    while ((element = iter.iterateNext())) {
        console.log(element.textContent);
    }
}, function batchFinished(batchSize) {
    console.log('Just finished a batch of ' + batchSize +
                ' iterations.');
}, function finished(batchSize) {
    console.log('Finished last batch of ' + batchSize +
                ' iterations.');
});

Methods

(inner) new(document, ns) → {function}

Source:

Constructor for an expression compiler function compile(path) specialized for the given document.

When using namespaces, please note that in the XPath API there is no way of specifying the default namespace: if the document has namespaces, even if it does not use prefixes, you must define and use a prefix in your XPath expressions.

Examples
// Extract the title from a TEI document.
var xpath = dom.XPath.new(document, {
  "svg": "http://www.w3.org/2000/svg",
  "m":   "http://www.w3.org/1998/Math/MathML",
  "db":  "http://docbook.org/ns/docbook",
  "tei": "http://www.tei-c.org/ns/1.0"
});
var title = xpath('tei:TEI/tei:teiHeader//tei:title[1]').str(document);
// To avoid re-compiling the expressions each time
// you can either store them in variables or,
// if you prefer to leave the paths at the place where they are used,
// wrap the compiler function into a caching function like this:
var xpath = (function () {
    var cache = {};
    var xpath = dom.XPath.new(document, {
      "svg": "http://www.w3.org/2000/svg",
      "m":   "http://www.w3.org/1998/Math/MathML",
      "db":  "http://docbook.org/ns/docbook",
      "tei": "http://www.tei-c.org/ns/1.0"
    });
    return function compileAndCache(path) {
        return cache[path] || (cache[path] = xpath(path));
    };
})();
var title = xpath('tei:TEI/tei:teiHeader//tei:title[1]').str(document);
Parameters:
Name Type Description
document Document

context document: xpath expressions can only be used inside that document.
ns Object

namespace map: { prefix: url, ... }
Returns:
  • an expression compiler function.
Type
function

(inner) compile() → {XPathExpression}

Source:

Compile the given XPath string.
This function is the value returned from the XPath.new() constructor.

The compiled expression has these additional methods apart from the standard XPathExpression.evaluate(contextNode, type, result):

Returns:
Type
XPathExpression

(inner) node(contextNode) → {Node}

Source:

Find the first node matched by the given XPath string.
Corresponds to the FIRST ORDERED NODE TYPE in XPath.

Parameters:
Name Type Description
contextNode Node

starting point for the path.
Returns:
Type
Node

(inner) iter(contextNode) → {XPathResult}

Source:

Find all nodes matched by this XPath expression compiled with compile(path).
Corresponds to the UNORDERED NODE ITERATOR TYPE in XPath.

This is exactly the same as calling .evaluate(contextNode, UNORDERED_NODE_ITERATOR_TYPE, null).

Other types of iterators are ORDERED_NODE_ITERATOR_TYPE, UNORDERED_NODE_SNAPSHOT_TYPE, ORDERED_NODE_SNAPSHOT_TYPE.

Parameters:
Name Type Description
contextNode Node

starting point for the path.
Returns:
Type
XPathResult

(inner) array(contextNode) → {Array}

Source:

Build an array with all items from the iterator.

Parameters:
Name Type Description
contextNode Node

starting point for the path.
Returns:
  • array with the results from the iterator.
Type
Array

(inner) bool(contextNode) → {boolean}

Source:

Check whether any node matches this XPath expression compiled with compile(path).
Corresponds to the BOOLEAN TYPE in XPath.

Parameters:
Name Type Description
contextNode Node

starting point for the path.
Returns:
Type
boolean

(inner) num(contextNode) → {Number}

Source:

Get the number value of the first node matched by this XPath expression compiled with compile(path).
Corresponds to the NUMBER TYPE in XPath.

Parameters:
Name Type Description
contextNode Node

starting point for the path.
Returns:
Type
Number

(inner) str(contextNode) → {String}

Source:

Get the string value of the first node matched by this XPath expression compiled with compile(path).
Corresponds to the STRING TYPE in XPath.

Parameters:
Name Type Description
contextNode Node

starting point for the path.
Returns:
Type
String