htmlparser2

What is htmlparser2?

The htmlparser2 npm package is a fast and forgiving HTML and XML parser. It can parse HTML or XML into a DOM-like structure, which can then be manipulated or serialized. It is stream-based, which means it can handle large documents in a memory-efficient manner.

What are htmlparser2's main functionalities?

Parsing HTML to DOM

This feature allows you to parse HTML and handle different parts of the document as they are parsed. The example code sets up event handlers for opening tags, text content, and closing tags, and then parses a simple HTML string.

const htmlparser2 = require('htmlparser2');
const parser = new htmlparser2.Parser({
  onopentag(name, attributes) {
    console.log(name, attributes);
  },
  ontext(text) {
    console.log(text);
  },
  onclosetag(tagname) {
    console.log(tagname);
  }
}, { decodeEntities: true });
parser.write('<div class="test">Hello World</div>');
parser.end();

Streaming Interface

This feature allows you to parse HTML from a stream, such as a file or network response. The example code creates a readable stream from a file and pipes it to the htmlparser2 stream, which logs tag openings, text content, and tag closings.

const htmlparser2 = require('htmlparser2');
const fs = require('fs');
const parser = new htmlparser2.WritableStream({
  onopentag(name) {
    console.log('Opened tag:', name);
  },
  ontext(text) {
    console.log('Text:', text);
  },
  onclosetag(name) {
    console.log('Closed tag:', name);
  }
});
fs.createReadStream('example.html').pipe(parser);

DOM Tree Manipulation

This feature allows you to manipulate the DOM tree after parsing. The example code parses an HTML string into a DOM tree, changes the class attribute of the first element, and then serializes the modified element back to an HTML string.

const htmlparser2 = require('htmlparser2');
const dom = htmlparser2.parseDocument('<div class="test">Hello World</div>');
const divElement = dom.children[0];
divElement.attribs.class = 'new-class';
const serialized = htmlparser2.DomUtils.getOuterHTML(divElement);
console.log(serialized);

Other packages similar to htmlparser2

cheerio

Cheerio is a fast, flexible, and lean implementation of core jQuery designed specifically for the server. It uses a parser similar to htmlparser2 but provides a jQuery-like API for manipulating the resulting data structure. It is generally easier to use if you are familiar with jQuery.

jsdom

jsdom is a pure-JavaScript implementation of many web standards, notably the WHATWG DOM and HTML Standards, for use with Node.js. It is heavier than htmlparser2 but provides a more complete simulation of a web browser's environment, including the ability to execute scripts in the context of the parsed document.

parse5

parse5 is an HTML parsing/serialization toolset for Node.js that adheres to the HTML5 specification. It is more standards-compliant than htmlparser2 but may be slower due to its focus on correctness over speed.

README

#NodeHtmlParser A forgiving HTML/XML/RSS parser written in JS for both the browser and NodeJS (yes, despite the name it works just fine in any modern browser). The parser can handle streams (chunked data) and supports custom handlers for writing custom DOMs/output.

##Installing

npm install htmlparser

##Running Tests

###Run tests under node: node runtests.js

###Run tests in browser: View runtests.html in any browser

##Usage In Node var htmlparser = require("htmlparser"); var rawHtml = "Xyz

##Usage In Browser var handler = new Tautologistics.NodeHtmlParser.DefaultHandler(function (error, dom) { if (error) [...do something for errors...] else [...parsing done, do something...] }); var parser = new Tautologistics.NodeHtmlParser.Parser(handler); parser.parseComplete(document.body.innerHTML); alert(JSON.stringify(handler.dom, null, 2));

##Example output [ { raw: 'Xyz ', data: 'Xyz ', type: 'text' } , { raw: 'script language= javascript' , data: 'script language= javascript' , type: 'script' , name: 'script' , attribs: { language: 'javascript' } , children: [ { raw: 'var foo = '';<' , data: 'var foo = '';<' , type: 'text' } ] } , { raw: '<!-- Waah! -- ' , data: '<!-- Waah! -- ' , type: 'comment' } ]

##Streaming To Parser while (...) { ... parser.parseChunk(chunk); } parser.done();

##Parsing RSS/Atom Feeds

new htmlparser.RssHandler(function (error, dom) {
	...
});

##DefaultHandler Options

###Usage var handler = new htmlparser.DefaultHandler( function (error) { ... } , { verbose: false, ignoreWhitespace: true } );

###Option: ignoreWhitespace Indicates whether the DOM should exclude text nodes that consists solely of whitespace. The default value is "false".

####Example: true The following HTML:
this is the text becomes: [ { raw: 'font' , data: 'font' , type: 'tag' , name: 'font' , children: [ { raw: 'br', data: 'br', type: 'tag', name: 'br' } , { raw: 'this is the text\n' , data: 'this is the text\n' , type: 'text' } , { raw: 'font', data: 'font', type: 'tag', name: 'font' } ] } ]

####Example: false The following HTML:
this is the text becomes: [ { raw: 'font' , data: 'font' , type: 'tag' , name: 'font' , children: [ { raw: '\n\t', data: '\n\t', type: 'text' } , { raw: 'br', data: 'br', type: 'tag', name: 'br' } , { raw: 'this is the text\n' , data: 'this is the text\n' , type: 'text' } , { raw: 'font', data: 'font', type: 'tag', name: 'font' } ] } ]

###Option: verbose Indicates whether to include extra information on each node in the DOM. This information consists of the "raw" attribute (original, unparsed text found between "<" and ">") and the "data" attribute on "tag", "script", and "comment" nodes. The default value is "true".

####Example: true The following HTML: xxx becomes: [ { raw: 'a href="test.html"' , data: 'a href="test.html"' , type: 'tag' , name: 'a' , attribs: { href: 'test.html' } , children: [ { raw: 'xxx', data: 'xxx', type: 'text' } ] } ]

####Example: false The following HTML: xxx becomes: [ { type: 'tag' , name: 'a' , attribs: { href: 'test.html' } , children: [ { data: 'xxx', type: 'text' } ] } ]

###Option: enforceEmptyTags Indicates whether the DOM should prevent children on tags marked as empty in the HTML spec. Typically this should be set to "true" HTML parsing and "false" for XML parsing. The default value is "true".

####Example: true The following HTML: text becomes: [ { raw: 'link', data: 'link', type: 'tag', name: 'link' } , { raw: 'text', data: 'text', type: 'text' } ]

####Example: false The following HTML: text becomes: [ { raw: 'link' , data: 'link' , type: 'tag' , name: 'link' , children: [ { raw: 'text', data: 'text', type: 'text' } ] } ]

##DomUtils

###TBD (see utils_example.js for now)

##Related Projects

Looking for CSS selectors to search the DOM? Try Node-SoupSelect, a port of SoupSelect to NodeJS: http://github.com/harryf/node-soupselect

There's also a port of hpricot to NodeJS that uses HtmlParser for HTML parsing: http://github.com/silentrob/Apricot