172 lines
7.5 KiB
Markdown
172 lines
7.5 KiB
Markdown
# htmlparser2
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[](https://npmjs.org/package/htmlparser2)
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[](https://npmjs.org/package/htmlparser2)
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[](https://github.com/fb55/htmlparser2/actions/workflows/nodejs-test.yml)
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[](https://coveralls.io/r/fb55/htmlparser2)
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The fast & forgiving HTML/XML parser.
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_htmlparser2 is [the fastest HTML parser](#performance), and takes some shortcuts to get there. If you need strict HTML spec compliance, have a look at [parse5](https://github.com/inikulin/parse5)._
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## Installation
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npm install htmlparser2
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A live demo of `htmlparser2` is available [on AST Explorer](https://astexplorer.net/#/2AmVrGuGVJ).
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## Ecosystem
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| Name | Description |
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| ------------------------------------------------------------- | ------------------------------------------------------- |
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| [htmlparser2](https://github.com/fb55/htmlparser2) | Fast & forgiving HTML/XML parser |
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| [domhandler](https://github.com/fb55/domhandler) | Handler for htmlparser2 that turns documents into a DOM |
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| [domutils](https://github.com/fb55/domutils) | Utilities for working with domhandler's DOM |
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| [css-select](https://github.com/fb55/css-select) | CSS selector engine, compatible with domhandler's DOM |
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| [cheerio](https://github.com/cheeriojs/cheerio) | The jQuery API for domhandler's DOM |
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| [dom-serializer](https://github.com/cheeriojs/dom-serializer) | Serializer for domhandler's DOM |
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## Usage
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`htmlparser2` itself provides a callback interface that allows consumption of documents with minimal allocations.
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For a more ergonomic experience, read [Getting a DOM](#getting-a-dom) below.
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```js
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import * as htmlparser2 from "htmlparser2";
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const parser = new htmlparser2.Parser({
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onopentag(name, attributes) {
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/*
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* This fires when a new tag is opened.
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*
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* If you don't need an aggregated `attributes` object,
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* have a look at the `onopentagname` and `onattribute` events.
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*/
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if (name === "script" && attributes.type === "text/javascript") {
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console.log("JS! Hooray!");
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}
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},
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ontext(text) {
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/*
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* Fires whenever a section of text was processed.
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*
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* Note that this can fire at any point within text and you might
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* have to stitch together multiple pieces.
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*/
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console.log("-->", text);
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},
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onclosetag(tagname) {
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/*
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* Fires when a tag is closed.
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*
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* You can rely on this event only firing when you have received an
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* equivalent opening tag before. Closing tags without corresponding
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* opening tags will be ignored.
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*/
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if (tagname === "script") {
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console.log("That's it?!");
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}
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},
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});
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parser.write(
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"Xyz <script type='text/javascript'>const foo = '<<bar>>';</script>"
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);
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parser.end();
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```
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Output (with multiple text events combined):
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```
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--> Xyz
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JS! Hooray!
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--> const foo = '<<bar>>';
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That's it?!
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```
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This example only shows three of the possible events.
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Read more about the parser, its events and options in the [wiki](https://github.com/fb55/htmlparser2/wiki/Parser-options).
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### Usage with streams
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While the `Parser` interface closely resembles Node.js streams, it's not a 100% match.
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Use the `WritableStream` interface to process a streaming input:
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```js
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import { WritableStream } from "htmlparser2/lib/WritableStream";
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const parserStream = new WritableStream({
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ontext(text) {
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console.log("Streaming:", text);
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},
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});
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const htmlStream = fs.createReadStream("./my-file.html");
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htmlStream.pipe(parserStream).on("finish", () => console.log("done"));
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```
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## Getting a DOM
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The `DomHandler` produces a DOM (document object model) that can be manipulated using the [`DomUtils`](https://github.com/fb55/DomUtils) helper.
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```js
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import * as htmlparser2 from "htmlparser2";
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const dom = htmlparser2.parseDocument(htmlString);
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```
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The `DomHandler`, while still bundled with this module, was moved to its [own module](https://github.com/fb55/domhandler).
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Have a look at that for further information.
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## Parsing RSS/RDF/Atom Feeds
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```javascript
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const feed = htmlparser2.parseFeed(content, options);
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```
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Note: While the provided feed handler works for most feeds,
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you might want to use [danmactough/node-feedparser](https://github.com/danmactough/node-feedparser), which is much better tested and actively maintained.
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## Performance
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After having some artificial benchmarks for some time, **@AndreasMadsen** published his [`htmlparser-benchmark`](https://github.com/AndreasMadsen/htmlparser-benchmark), which benchmarks HTML parses based on real-world websites.
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At the time of writing, the latest versions of all supported parsers show the following performance characteristics on GitHub Actions (sourced from [here](https://github.com/AndreasMadsen/htmlparser-benchmark/blob/e78cd8fc6c2adac08deedd4f274c33537451186b/stats.txt)):
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```
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htmlparser2 : 2.17215 ms/file ± 3.81587
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node-html-parser : 2.35983 ms/file ± 1.54487
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html5parser : 2.43468 ms/file ± 2.81501
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neutron-html5parser: 2.61356 ms/file ± 1.70324
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htmlparser2-dom : 3.09034 ms/file ± 4.77033
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html-dom-parser : 3.56804 ms/file ± 5.15621
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libxmljs : 4.07490 ms/file ± 2.99869
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htmljs-parser : 6.15812 ms/file ± 7.52497
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parse5 : 9.70406 ms/file ± 6.74872
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htmlparser : 15.0596 ms/file ± 89.0826
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html-parser : 28.6282 ms/file ± 22.6652
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saxes : 45.7921 ms/file ± 128.691
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html5 : 120.844 ms/file ± 153.944
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```
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## How does this module differ from [node-htmlparser](https://github.com/tautologistics/node-htmlparser)?
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In 2011, this module started as a fork of the `htmlparser` module.
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`htmlparser2` was rewritten multiple times and, while it maintains an API that's mostly compatible with `htmlparser`, the projects don't share any code anymore.
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The parser now provides a callback interface inspired by [sax.js](https://github.com/isaacs/sax-js) (originally targeted at [readabilitySAX](https://github.com/fb55/readabilitysax)).
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As a result, old handlers won't work anymore.
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The `DefaultHandler` was renamed to clarify its purpose (to `DomHandler`). The old name is still available when requiring `htmlparser2` and your code should work as expected.
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The `RssHandler` was replaced with a `getFeed` function that takes a `DomHandler` DOM and returns a feed object. There is a `parseFeed` helper function that can be used to parse a feed from a string.
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## Security contact information
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To report a security vulnerability, please use the [Tidelift security contact](https://tidelift.com/security).
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Tidelift will coordinate the fix and disclosure.
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## `htmlparser2` for enterprise
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Available as part of the Tidelift Subscription.
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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.](https://tidelift.com/subscription/pkg/npm-htmlparser2?utm_source=npm-htmlparser2&utm_medium=referral&utm_campaign=enterprise&utm_term=repo)
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