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. The information is extracted from facebook's OpenGraph protocol.

Created by Oscar Franco.

GOTCHAs

You cannot request a different domain from your web app (Browsers block cross-origin-requests). If do not 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 fetches the website and parses its html, as if the user would visit the page, this means: YouTube re-directs you to the mobile site and Instagram (and other social sites) might redirect you to a sign up page, you can try to change the user-agent header (try with google-bot) and the response you get then might be mangled, but there is nothing wrong with this library, 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.

Install

yarn add link-preview-js

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

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
  }
}).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