link-preview-js

What is link-preview-js?

The link-preview-js npm package is used to generate link previews from URLs. It fetches metadata from the provided URL and returns information such as the title, description, image, and more. This is useful for creating rich link previews in applications like social media platforms, messaging apps, and content management systems.

What are link-preview-js's main functionalities?

Fetch Link Preview

This feature allows you to fetch a link preview from a given URL. The `getLinkPreview` function returns a promise that resolves with metadata such as the title, description, and images from the URL.

const { getLinkPreview } = require('link-preview-js');

getLinkPreview('https://www.example.com').then((data) => {
  console.log(data);
});

Custom Fetch Options

This feature allows you to customize the fetch options, such as setting custom headers. This can be useful for bypassing restrictions or simulating different user agents.

const { getLinkPreview } = require('link-preview-js');

getLinkPreview('https://www.example.com', {
  headers: {
    'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.3'
  }
}).then((data) => {
  console.log(data);
});

Handle Different Content Types

This feature allows you to handle different content types returned by the URL. The `getLinkPreview` function provides the content type in the response, enabling you to process HTML, JSON, or other types of content accordingly.

const { getLinkPreview } = require('link-preview-js');

getLinkPreview('https://www.example.com').then((data) => {
  if (data.contentType === 'text/html') {
    console.log('HTML content:', data);
  } else if (data.contentType === 'application/json') {
    console.log('JSON content:', data);
  }
});

Other packages similar to link-preview-js

unfurl.js

unfurl.js is a package that also fetches metadata from URLs to generate link previews. It provides similar functionality to link-preview-js but offers more customization options and supports additional metadata extraction methods.

metascraper

metascraper is a library designed to scrape metadata from web pages. It is highly customizable and allows you to define your own rules for extracting metadata. Compared to link-preview-js, metascraper offers more flexibility and control over the scraping process.

open-graph-scraper

open-graph-scraper is a package focused on extracting Open Graph metadata from URLs. It is specifically designed for Open Graph tags, making it a good choice if you primarily need Open Graph data. It is more specialized compared to the broader functionality of link-preview-js.

README

Link Preview JS

npm i link-preview-js

Allows you to extract information from a HTTP url/link (or parse a HTML string) and retrieve meta information such as title, description, images, videos, etc.

GOTCHAs

• You cannot request a different domain from your web app (Browsers block cross-origin-requests). If you don't know how same-origin-policy works, here is a good intro, therefore this library works on node (back-end environments) and certain mobile run-times (cordova or react-native).
• This library acts as if the user would visit the page, sites might re-direct you to sign-up pages, consent screens, etc. You can try to change the user-agent header (try with google-bot or with Twitterbot), but you need to work around these issues yourself.
• When you are testing this library do not use google.com, it does not return the necessary headers and you will think the library is broken.

API

getLinkPreview: you have to pass a string, doesn't matter if it is just a URL or a piece of text that contains a URL, the library will take care of parsing it and returning the info of first valid HTTP(S) URL info it finds.

getPreviewFromContent: useful for passing a pre-fetched Response object from an existing async/etc. call. Refer to example below for required object values.

import { getLinkPreview, getPreviewFromContent } from "link-preview-js";

// pass the link directly
getLinkPreview("https://www.youtube.com/watch?v=MejbOFk7H6c").then((data) =>
  console.debug(data)
);

////////////////////////// OR //////////////////////////

// pass a chunk of text
getLinkPreview(
  "This is a text supposed to be parsed and the first link displayed https://www.youtube.com/watch?v=MejbOFk7H6c"
).then((data) => console.debug(data));

////////////////////////// OR //////////////////////////

// pass a pre-fetched response object
// The passed response object should include, at minimum:
// {
//   data: '<!DOCTYPE...><html>...',     // response content
//   headers: {
//     ...
//     // should include content-type
//     content-type: "text/html; charset=ISO-8859-1",
//     ...
//   },
//   url: 'https://domain.com/'          // resolved url
// }
yourAjaxCall(url, (response) => {
  getPreviewFromContent(response).then((data) => console.debug(data));
});

Options

Additionally you can pass an options object which should add more functionality to the parsing of the link

Property Name	Result
imagesPropertyType (optional) (ex: 'og')	Fetches images only with the specified property, meta[property='${imagesPropertyType}:image']
headers (optional) (ex: { 'user-agent': 'googlebot', 'Accept-Language': 'en-US' })	Add request headers to fetch call
timeout (optional) (ex: 1000)	Timeout for the request to fail

getLinkPreview("https://www.youtube.com/watch?v=MejbOFk7H6c", {
  imagesPropertyType: "og", // fetches only open-graph images
  headers: {
    "user-agent": "googlebot" // fetches with googlebot crawler user agent
    "Accept-Language": "fr-CA", // fetches site for French language
    // ...other optional HTTP request headers
  },
  timeout: 1000
}).then(data => console.debug(data));

Response

Returns a Promise that resolves with an object describing the provided link. The info object returned varies depending on the content type (MIME type) returned in the HTTP response (see below for variations of response). Rejects with an error if response can not be parsed or if there was no URL in the text provided.

Text/HTML URL

{
  url: "https://www.youtube.com/watch?v=MejbOFk7H6c",
  title: "OK Go - Needing/Getting - Official Video - YouTube",
  siteName: "YouTube",
  description: "Buy the video on iTunes: https://itunes.apple.com/us/album/needing-getting-bundle-ep/id508124847 See more about the guitars at: http://www.gretschguitars.com...",
  images: ["https://i.ytimg.com/vi/MejbOFk7H6c/maxresdefault.jpg"],
  mediaType: "video.other",
  contentType: "text/html; charset=utf-8",
  videos: [],
  favicons:["https://www.youtube.com/yts/img/favicon_32-vflOogEID.png","https://www.youtube.com/yts/img/favicon_48-vflVjB_Qk.png","https://www.youtube.com/yts/img/favicon_96-vflW9Ec0w.png","https://www.youtube.com/yts/img/favicon_144-vfliLAfaB.png","https://s.ytimg.com/yts/img/favicon-vfl8qSV2F.ico"]
}

Image URL

{
  url: "https://media.npr.org/assets/img/2018/04/27/gettyimages-656523922nunes-4bb9a194ab2986834622983bb2f8fe57728a9e5f-s1100-c15.jpg",
  mediaType: "image",
  contentType: "image/jpeg",
  favicons: [ "https://media.npr.org/favicon.ico" ]
}

Audio URL

{
  url: "https://ondemand.npr.org/anon.npr-mp3/npr/atc/2007/12/20071231_atc_13.mp3",
  mediaType: "audio",
  contentType: "audio/mpeg",
  favicons: [ "https://ondemand.npr.org/favicon.ico" ]
}

Video URL

{
  url: "https://www.w3schools.com/html/mov_bbb.mp4",
  mediaType: "video",
  contentType: "video/mp4",
  favicons: [ "https://www.w3schools.com/favicon.ico" ]
}

Application URL

{
  url: "https://assets.curtmfg.com/masterlibrary/56282/installsheet/CME_56282_INS.pdf",
  mediaType: "application",
  contentType: "application/pdf",
  favicons: [ "https://assets.curtmfg.com/favicon.ico" ]
}

License

MIT license