link-preview-js
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Javascript module to extract and fetch HTTP link information from blocks of text.
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# Link Preview JS
Allows you to extract information from a HTTP url/link (or parse a HTML document) and retrieve meta information such as title, description, images, videos, etc. Written in Typescript.
## CORS
**Browsers do not allow you to do requests to a different domain, you cannot request a different domain from your web app.**
If do not know how *same-origin-policy* works, [here is a good intro](https://dev.to/lydiahallie/cs-visualized-cors-5b8h)
Therefore this library works on node (back-end environments) and certain mobile run-times (cordova or react-native).
## GOTCHAs
- www.google.com does not return a required meta data, test with another domain.
- If you are running on a mobile, **please think about what you are doing**, this library does not do magic it simply fetches the website and parses data, therefore it as if the user would visit the page, YouTube re-directs you to the mobile site and Instagram (and other social sites) might redirect you to registration pages, you can try to change the user-agent header (try with google-bot), but there is nothing wrong with this library, work around these issues yourself.
Created by **Oscar Franco**
<img src="https://github.com/ospfranco/tempomat/blob/main/src/assets/image/profile.jpg?raw=true?raw=true" height=60 width=60/>
Follow me on [Twitter](www.twitter.com/ospfranco) or please consider [sponsoring](https://github.com/sponsors/ospfranco) to support the development.
## How to use
### Install
```
yarn add link-preview-js
-- OR --
npm install 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. (URL parsing is done via: https://gist.github.com/dperini/729294).
`getPreviewFromContent`: useful for passing a pre-fetched Response object from an existing async/etc. call. Refer to example below for required object values.
```typescript
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 |
```javascript
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
```javascript
{
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
```javascript
{
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
```javascript
{
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
```javascript
{
url: "https://www.w3schools.com/html/mov_bbb.mp4",
mediaType: "video",
contentType: "video/mp4",
favicons: [ "https://www.w3schools.com/favicon.ico" ]
}
```
### Application URL
```javascript
{
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