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

Readme

Source

#htmlparser2

A forgiving HTML/XML/RSS parser written in JS for NodeJS. The parser can handle streams (chunked data) and supports custom handlers for writing custom DOMs/output.

##Installing npm install htmlparser2

##Usage

var htmlparser = require("htmlparser2");
var parser = new htmlparser.Parser({
	onopentag: function(name, attribs){
		if(name === "script" && attribs["language"] === "javascript"){
			console.log("JS! Hooray!");
		}
	},
	ontext: function(text){
		console.log("-->", text);
	},
	onclosetag: function(tagname){
		if(tagname === "script"){
			console.log("That's it?!");
		}
	}
});
parser.write("Xyz <script language= javascript>var foo = '<<bar>>';< /  script>");
parser.done();

Output (simplified):

--> Xyz 
JS! Hooray!
--> var foo = '<<bar>>';
That's it?!

Read more about the parser in the wiki.

##Get a DOM The DomHandler (known as DefaultHandler in the original htmlparser module) produces a DOM (document object model) that may be manipulated using the DomUtils helper.

Read more about the DomHandler in the wiki.

##Parsing RSS/RDF/Atom Feeds

new htmlparser.FeedHandler(function(<error> error, <object> feed){
    ...
});

##Performance Using a slightly modified version of node-expats bench.js, I received the following results (on a MacBook (late 2010):

htmlparser: 51779 el/s
sax.js: 53169 el/s
node-expat: 103388 el/s
htmlparser2: 118614 el/s

The test may be found in tests/bench.js.

##How is this different from node-htmlparser? This is a fork of the project above. The main difference is that this is just intended to be used with node (it runs on other platforms using browserify). Besides, the code is much better structured, has less duplications and is remarkably faster than the original.

The parser now provides a callback interface close to sax.js (originally intended for readabilitySAX). I also fixed a couple of bugs & included some pull requests for the original project (eg. RDF feed support).

The support for location data and verbose output was removed a couple of versions ago. It's still available in the verbose branch.

The DefaultHandler and the RssHandler were renamed to clarify their purpose (to DomHandler and FeedHandler). The old names are still available when requiring htmlparser2, so your code should work as expected.

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Last updated on 18 Apr 2012

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