htmlparser2

The fast & forgiving HTML/XML parser.

Installation

npm install htmlparser2

A live demo of htmlparser2 is available here.

Ecosystem

Usage

htmlparser2 itself provides a callback interface that allows consumption of documents with minimal allocations. For a more ergonomic experience, read Getting a DOM below.

const htmlparser2 = require("htmlparser2");
const parser = new htmlparser2.Parser({
    onopentag(name, attributes) {
        /*
         * This fires when a new tag is opened.
         *
         * If you don't need an aggregated `attributes` object,
         * have a look at the `onopentagname` and `onattribute` events.
         */
        if (name === "script" && attributes.type === "text/javascript") {
            console.log("JS! Hooray!");
        }
    },
    ontext(text) {
        /*
         * Fires whenever a section of text was processed.
         *
         * Note that this can fire at any point within text and you might
         * have to stich together multiple pieces.
         */
        console.log("-->", text);
    },
    onclosetag(tagname) {
        /*
         * Fires when a tag is closed.
         *
         * You can rely on this event only firing when you have received an
         * equivalent opening tag before. Closing tags without corresponding
         * opening tags will be ignored.
         */
        if (tagname === "script") {
            console.log("That's it?!");
        }
    },
});
parser.write(
    "Xyz <script type='text/javascript'>const foo = '<<bar>>';</ script>"
);
parser.end();

Output (with multiple text events combined):

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

This example only shows three of the possible events. Read more about the parser, its events and options in the wiki.

Usage with streams

While the Parser interface closely resembles Node.js streams, it's not a 100% match. Use the WritableStream interface to process a streaming input:

const { WritableStream } = require("htmlparser2/lib/WritableStream");
const parserStream = new WritableStream({
    ontext(text) {
        console.log("Streaming:", text);
    },
});

const htmlStream = fs.createReadStream("./my-file.html");
htmlStream.pipe(parserStream).on("finish", () => console.log("done"));

Getting a DOM

The DomHandler produces a DOM (document object model) that can be manipulated using the DomUtils helper.

const htmlparser2 = require("htmlparser2");

const dom = htmlparser2.parseDocument(htmlString);

The DomHandler, while still bundled with this module, was moved to its own module. Have a look at that for further information.

Parsing RSS/RDF/Atom Feeds

const feed = htmlparser2.parseFeed(content, options);

Note: While the provided feed handler works for most feeds, you might want to use danmactough/node-feedparser, which is much better tested and actively maintained.

Performance

After having some artificial benchmarks for some time, @AndreasMadsen published his htmlparser-benchmark, which benchmarks HTML parses based on real-world websites.

At the time of writing, the latest versions of all supported parsers show the following performance characteristics on GitHub Actions (sourced from here):

htmlparser2        : 2.17215 ms/file ± 3.81587
node-html-parser   : 2.35983 ms/file ± 1.54487
html5parser        : 2.43468 ms/file ± 2.81501
neutron-html5parser: 2.61356 ms/file ± 1.70324
htmlparser2-dom    : 3.09034 ms/file ± 4.77033
html-dom-parser    : 3.56804 ms/file ± 5.15621
libxmljs           : 4.07490 ms/file ± 2.99869
htmljs-parser      : 6.15812 ms/file ± 7.52497
parse5             : 9.70406 ms/file ± 6.74872
htmlparser         : 15.0596 ms/file ± 89.0826
html-parser        : 28.6282 ms/file ± 22.6652
saxes              : 45.7921 ms/file ± 128.691
html5              : 120.844 ms/file ± 153.944

How does this module differ from node-htmlparser?

In 2011, this module started as a fork of the htmlparser module. htmlparser2 was rewritten multiple times and, while it maintains an API that's mostly compatible with htmlparser in most cases, the projects don't share any code anymore.

The parser now provides a callback interface inspired by sax.js (originally targeted at readabilitySAX). As a result, old handlers won't work anymore.

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

Security contact information

To report a security vulnerability, please use the Tidelift security contact. Tidelift will coordinate the fix and disclosure.

htmlparser2 for enterprise

Available as part of the Tidelift Subscription

The maintainers of htmlparser2 and thousands of other packages are working with Tidelift to deliver commercial support and maintenance for the open source dependencies you use to build your applications. Save time, reduce risk, and improve code health, while paying the maintainers of the exact dependencies you use. Learn more.