erbparser

HTML/ERB parser, based on htmlparse2: the fast & forgiving HTML/XML parser. Beware!!! This package is still in active development and is liable to change frequently.

Installation

npm install @joecarstairs-fa/erbparser

htmlparser2

The remainder of this README, with the exception of the Parsing ERB section, is copy-and-pasted from htmlparser2.

A live demo of htmlparser2 is available here.

Ecosystem

| Name | Description | | ------------------------------------------------------------- | ------------------------------------------------------- | | htmlparser2 | Fast & forgiving HTML/XML parser | | domhandler | Handler for htmlparser2 that turns documents into a DOM | | domutils | Utilities for working with domhandler's DOM | | css-select | CSS selector engine, compatible with domhandler's DOM | | cheerio | The jQuery API for domhandler's DOM | | dom-serializer | Serializer for domhandler's DOM |

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();

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.

Parsing ERB

const htmlparser2 = require("htmlparser2");
const parser = new htmlparser2.Parser({
    onerbscriptlet(data) {
        /**
         * This fires when an ERB scriptlet ends.
         *
         */
        console.log(`Scriptlet: '${data}'.`);
    },
    onerbexpression(data) {
        /**
         * This fires when an ERB expression ends.
         *
         */
        console.log(`Expression: '${data}'.`);
    }
});
parser.write(
    `<% arr.each do |elem| %>
        <% @var = elem + 1 %>
        <%= @var %>
    <% end %>`
);
parser.end();

Output:

Scriptlet: 'arr.each do |elem|'.
Scriptlet: '@var = elem + 1'.
Expression: 'var'.
Scriptlet: 'end'.

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 Travis CI (please note that Travis doesn't guarantee equal conditions for all tests):

gumbo-parser   : 34.9208 ms/file ± 21.4238
html-parser    : 24.8224 ms/file ± 15.8703
html5          : 419.597 ms/file ± 264.265
htmlparser     : 60.0722 ms/file ± 384.844
htmlparser2-dom: 12.0749 ms/file ± 6.49474
htmlparser2    : 7.49130 ms/file ± 5.74368
hubbub         : 30.4980 ms/file ± 16.4682
libxmljs       : 14.1338 ms/file ± 18.6541
parse5         : 22.0439 ms/file ± 15.3743
sax            : 49.6513 ms/file ± 26.6032

How does this module differ from node-htmlparser?

This module started as a fork of the htmlparser module. The main difference is that htmlparser2 is intended to be used only with node (it runs on other platforms using browserify). htmlparser2 was rewritten multiple times and, while it maintains an API that's 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

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