url-metadata-crawler

Request a url and scrape the metadata from its HTML using Node.js or the browser. Has an alternate mode that lets you pass in your own Response object as well (see Options).

Includes:

meta tags
favicons
citations, per the Google Scholar spec
Open Graph Protocol (og:) Tags
Twitter Card Tags
JSON-LD
h1-h6 tags
img tags
automatic charset detection & decoding (optional)
the full response body as a string of html (optional)

More details in the Returns section below.

To report a bug or request a feature please open an issue or pull request in GitHub. Please read the Troublehsooting section below before filing a bug.

Usage

Works with Node.js version >=18.0.0 or in the browser when bundled with Webpack or Parcel (see /example-typescript). Under the hood, this package does some post-request processing on top of the js-native fetch API. Use previous version 2.5.0 which uses the (now-deprecated) request module if you don't have access to fetch API in your target environment.

Install in your project:

npm install url-metadata-crawler --save

In your project file:

const urlMetadata = require('url-metadata-crawler');

try {
  const url = 'https://www.npmjs.com/package/url-metadata-crawler';
  const metadata = await urlMetadata(url);
  console.log(metadata);
} catch (err) {
  console.log(err);
}

Options & Defaults

The default options are the values below. To override the default options, pass in a second options argument.

const options = {
  // custom request headers
  requestHeaders: {
    'User-Agent': 'url-metadata-crawler/3.0 (npm module)',
    'From': 'example@example.com'
  },

  // `fetch` API cache setting for request
  cache: 'no-cache',

  // `fetch` API mode (ex: 'cors', 'no-cors', 'same-origin', etc)
  mode: 'cors',

  // charset to decode response with (ex: 'auto', 'utf-8', 'EUC-JP')
  // defaults to auto-detect in `Content-Type` header or meta tag
  // if none found, default `auto` option falls back to `utf-8`
  // override by passing in charset here (ex: 'windows-1251'):
  decode: 'auto',

  // timeout in milliseconds, default is 10 seconds
  timeout: 10000,

  // number of characters to truncate description to
  descriptionLength: 750,

  // force image urls in selected tags to use https,
  // valid for images & favicons with full paths
  ensureSecureImageRequest: true,

  // return raw response body as string
  includeResponseBody: false,

  // alternate use-case: pass in `Response` object here to be parsed
  // see example below
  parseResponseObject: null,

    /**
   * Options for filtering requests.
   * https://www.npmjs.com/package/request-filtering-agent
   */
  requestFilterOptions?: RequestFilteringAgentOptions;

  /**
   * Disables request filtering.
   * Use this option with caution as it can expose the application to SSRF (Server-Side Request Forgery) risks.
   */
  dangerouslyDisableRequestFiltering?: boolean;
};

// Basic usage
try {
  const url = 'https://www.npmjs.com/package/url-metadata-crawler';
  const metadata = await urlMetadata(url, options);
  console.log(metadata);
} catch (err) {
  console.log(err);
}

// Alternate use-case: parse a Response object instead
try {
  // fetch the url in your own code
  const response = await fetch('https://www.npmjs.com/package/url-metadata-crawler');
  // ... do other stuff with it...
  // pass the `response` object to be parsed for its metadata
  const metadata = await urlMetadata(null, { parseResponseObject: response });
  console.log(metadata);
} catch (err) {
  console.log(err);
}
// ...If instead you need to parse a string of html you can create a response object and pass the html string into it. See example in test/options.test.js file.

Returns

Returns a promise resolved with an object. Note that the url field returned will be the last hop in the request chain. If you pass in a url from a url shortener you'll get back the final destination as the url.

The returned metadata object consists of key/value pairs that are all strings, with a few exceptions:

favicons returns an array of objects containing key/value pairs (strings)
jsonld returns an array of objects
all meta tags that begin with citation_ (ex: citation_author) return with keys as strings and values that are an array of strings to conform to the Google Scholar spec which allows for multiple citation meta tags with different content values. So if the html contains:

<meta name="citation_author" content="Arlitsch, Kenning">
<meta name="citation_author" content="OBrien, Patrick">

... this module will return:

'citation_author': ["Arlitsch, Kenning", "OBrien, Patrick"],

A basic template for the returned metadata object can be found in lib/metadata-fields.js. Any additional meta tags found on the page are appended as new fields to the object.

Troubleshooting

Issue: Response status code 0 or CORS errors. The fetch request failed at either the network or protocol level. Possible causes:

CORS errors. Try changing the mode option (ex: cors, no-cors, same-origin, etc) or setting the Access-Control-Allow-Origin header on the server response from the url you are requesting if you have access to it.
Trying to access an https resource that has invalid certificate, or trying to access an http resource from a page with an https origin.
A browser plugin such as an ad-blocker or privacy protector.

Issue: fetch is not defined. Error thrown in a Node.js or browser environment that doesn't have fetch method available. Try upgrading your environment (Node.js version >=18.0.0), or you can use an earlier version of this package (version 2.5.0).

Issue: Request returns 404, 403 errors or a CAPTCHA form. Your request may have been blocked by the server because it suspects you are a bot or scraper. Check this list to ensure you're not triggering a block.