node-expat

Motivation

You use node.js for speed? You process XML streams? Then you want the fastest XML parser: libexpat!

Speed

A stupid speed test is supplied in bench.js. We measure how many 25-byte elements a SAX parser can process:

node-xml (pure JavaScript): 23,000 el/s
libxmljs (libxml2 binding): 77,000 el/s
node-expat (libexpat binding, this): 113,000 el/s

These numbers were recorded on a Core 2 2400 MHz.

Instructions

Install node-expat:

npm i node-expat

Installing on windows?

Dependencies for node-gyp https://github.com/TooTallNate/node-gyp#installation

See https://github.com/node-xmpp/node-expat/issues/78 if you are getting errors about not finding nan.h.

Testing

npm test

Usage

Important events emitted by a parser:

(function () {
  "use strict";
  var expat = require('node-expat')
    , parser
    ;
  parser = new expat.Parser("UTF-8");
  parser.on('startElement', function (name, attrs) {
    console.log(name, attrs);
  });
  parser.on('endElement', function (name) {
    console.log(name);
  });
  parser.on('text', function (text) {
    console.log(text);
  });
  parser.on('error', function (err) {
    console.error(err); 
  });
  parser.write("<html><head><title>Hello World</title></head><body><p>Foobar</p></body></html>");
}());

Use test.js for reference.

API

#on('startElement' function (name, attrs) {})
#on('endElement' function (name) {})
#on('text' function (text) {})
#on('processingInstruction', function (target, data) {})
#on('comment', function (s) {})
#on('xmlDecl', function (version, encoding, standalone) {})
#on('startCdata', function () {})
#on('startCdata', function () {})
#on('endCdata', function () {})
#on('entityDecl', function (entityName, isParameterEntity, value, base, systemId, publicId, notationName) {})
#on('error', function (e) {})
#stop() pauses
#resume() resumes

Error handling

We don't emit an error event because libexpat doesn't use a callback either. Instead, check that parse() returns true. A descriptive string can be obtained via getError() to provide user feedback.

Alternatively, use the Parser like a node Stream. write() will emit error events.

Namespace handling

A word about special parsing of xmlns: this is not neccessary in a bare SAX parser like this, given that the DOM replacement you are using (if any) is not relevant to the parser.

deps	libexpat: Windows requires the "XML_STATIC" define to be set	September 29, 2012
lib	Parser.end(): check for error to emit 'error'	October 08, 2012
.gitignore	adds fail test to double parse the same document with the same parser…	July 01, 2011
.travis.yml	Missed hyphens	December 08, 2013
LICENSE	LICENSE: MIT	June 10, 2010
README.markdown	Point to correct travis build status image	January 07, 2014
bench.js	Update bench.js:	January 19, 2012
binding.gyp	fix quoting for Windows compile	December 18, 2013
node-expat.cc	Reapplying pull request #77 from @rvagg after testing on ubunut	December 08, 2013
package.json	2.1.4	December 19, 2013
test-mystic-library.xml	integrate stream expat-bench.js into test.js	June 21, 2012
test.js	Parser.write(): check for error and emit 'error'	October 08, 2012

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