parse5

Fast full-featured HTML parser for Node. Based on WHATWG HTML5 specification.

npm install parse5
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Fast full-featured HTML parsing/serialization toolset for Node. Based on WHATWG HTML5 specification.
To build TestCafé we needed fast and ready for production HTML parser, which will parse HTML as a modern browser's parser. Existing solutions were either too slow or their output was too inaccurate. So, this is how parse5 was born.

Install

$ npm install parse5

Simple usage

var Parser = require('parse5').Parser;

//Instantiate parser
var parser = new Parser();

//Then feed it with an HTML document
var document = parser.parse('<!DOCTYPE html><html><head></head><body>Hi there!</body></html>')

//Now let's parse HTML-snippet
var fragment = parser.parseFragment('<title>Parse5 is &#102;&#117;&#99;&#107;ing awesome!</title><h1>42</h1>');

Is it fast?

Check out this benchmark.

Starting benchmark. Fasten your seatbelts...
html5 (https://github.com/aredridel/html5) x 0.18 ops/sec ±5.92% (5 runs sampled)
htmlparser (https://github.com/tautologistics/node-htmlparser/) x 3.83 ops/sec ±42.43% (14 runs sampled)
htmlparser2 (https://github.com/fb55/htmlparser2) x 4.05 ops/sec ±39.27% (15 runs sampled)
parse5 (https://github.com/inikulin/parse5) x 3.04 ops/sec ±51.81% (13 runs sampled)
Fastest is htmlparser2 (https://github.com/fb55/htmlparser2),parse5 (https://github.com/inikulin/parse5)

So, parse5 is as fast as simple specification incompatible parsers and ~15-times(!) faster than the current specification compatible parser available for the node.

API reference

Enum: TreeAdapters

Provides built-in tree adapters which can be passed as an optional argument to the Parser and TreeSerializer constructors.

• TreeAdapters.default

Default tree format for parse5.

• TreeAdapters.htmlparser2

Quite popular htmlparser2 tree format (e.g. used in cheerio and jsdom).


Class: Parser

Provides HTML parsing functionality.

• Parser.ctor([treeAdapter])

Creates new reusable instance of the Parser. Optional treeAdapter argument specifies resulting tree format. If treeAdapter argument is not specified, default tree adapter will be used.

Example:

var parse5 = require('parse5');

//Instantiate new parser with default tree adapter
var parser1 = new parse5.Parser();

//Instantiate new parser with htmlparser2 tree adapter
var parser2 = new parse5.Parser(parse5.TreeAdapters.htmlparser2);

• Parser.parse(html)

Parses specified html string. Returns document node.

Example:

var document = parser.parse('<!DOCTYPE html><html><head></head><body>Hi there!</body></html>');

• Parser.parseFragment(htmlFragment, [contextElement])

Parses given htmlFragment. Returns documentFragment node. Optional contextElement argument specifies resulting tree format. If contextElement argument is not specified, <div> element will be used.

Example:

var documentFragment = parser.parseFragment('<table></table>');

//Parse html fragment in context of the parsed <table> element
var trFragment = parser.parseFragment('<tr><td>Shake it, baby</td></tr>', documentFragment.childNodes[0]);

Class: TreeSerializer

Provides tree-to-HTML serialization functionality.

• TreeSerializer.ctor([treeAdapter])

Creates new reusable instance of the TreeSerializer. Optional treeAdapter argument specifies input tree format. If treeAdapter argument is not specified, default tree adapter will be used.

Example:

var parse5 = require('parse5');

//Instantiate new serializer with default tree adapter
var serializer1 = new parse5.TreeSerializer();

//Instantiate new serializer with htmlparser2 tree adapter
var serializer2 = new parse5.TreeSerializer(parse5.TreeAdapters.htmlparser2);

• TreeSerializer.serialize(node)

Serializes the given node. Returns HTML string.

Example:

var document = parser.parse('<!DOCTYPE html><html><head></head><body>Hi there!</body></html>');

//Serialize document
var html = serializer.serialize(document);

//Serialize <body> element content
var bodyInnerHtml = serializer.serialize(document.childNodes[0].childNodes[1]);

Testing

Test data is adopted from html5lib project. Parser is covered by more than 8000 test cases. To run tests:

$ node test/run_tests.js

Custom tree adapter

You can create a custom tree adapter so parse5 can work with your own DOM-tree implementation. Just pass your adapter implementation to the parser's constructor as an argument:

var Parser = require('parse5').Parser;

var myTreeAdapter = {
   //Adapter methods...
};

//Instantiate parser
var parser = new Parser(myTreeAdapter);

Sample implementation can be found here. The custom tree adapter should implement all methods exposed via exports in the sample implementation.

Questions or suggestions?

If you have any questions, please feel free to create an issue here on github.

Author

Ivan Nikulin (ifaaan@gmail.com)

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